U.S. patent application number 15/061953 was filed with the patent office on 2016-09-22 for scheduling enhancements for contention-based shared frequency spectrum.
The applicant listed for this patent is QUALCOMM Incorporated. Invention is credited to Wanshi CHEN, Tao LUO, Srinivas YERRAMALLI.
Application Number | 20160278118 15/061953 |
Document ID | / |
Family ID | 55590164 |
Filed Date | 2016-09-22 |
United States Patent
Application |
20160278118 |
Kind Code |
A1 |
YERRAMALLI; Srinivas ; et
al. |
September 22, 2016 |
SCHEDULING ENHANCEMENTS FOR CONTENTION-BASED SHARED FREQUENCY
SPECTRUM
Abstract
Channel availability is uncertain when employing an unlicensed
carrier. In particular, it may be difficult to schedule grants in
advance because of the uncertainty associated with future channels
availability. Accordingly, scheduling UL and/or DL grants
exclusively using self-scheduling or exclusively using
cross-carrier scheduling for utilizing an unlicensed carrier may
result in wasted communication opportunities. Aspects disclosed
herein whereby an eNB may use licensed and unlicensed carriers to
communicate downlink grants and uplink grants for an unlicensed
carrier to a UE. In one aspect, the eNB may use an unlicensed
carrier to communicate downlink grants for downlink communication
on the unlicensed carrier, and may use a licensed carrier to
communicate uplink grants for uplink communication on the
unlicensed carrier.
Inventors: |
YERRAMALLI; Srinivas; (San
Diego, CA) ; LUO; Tao; (San Diego, CA) ; CHEN;
Wanshi; (San Diego, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
QUALCOMM Incorporated |
San Diego |
CA |
US |
|
|
Family ID: |
55590164 |
Appl. No.: |
15/061953 |
Filed: |
March 4, 2016 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62134487 |
Mar 17, 2015 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 72/1289 20130101;
H04L 5/0094 20130101; H04L 5/0053 20130101; H04W 72/0453 20130101;
H04W 16/14 20130101; H04L 5/0007 20130101; H04L 5/001 20130101;
H04L 5/06 20130101; H04W 24/08 20130101 |
International
Class: |
H04W 72/14 20060101
H04W072/14; H04W 72/12 20060101 H04W072/12; H04W 24/08 20060101
H04W024/08; H04W 72/04 20060101 H04W072/04 |
Claims
1. A method for wireless communication by a user equipment (UE),
comprising: receiving a downlink (DL) grant for a secondary carrier
and an uplink (UL) grant for the secondary carrier, wherein the DL
grant is received on the secondary carrier and the UL grant is
received on a primary carrier; receiving DL data on the secondary
carrier after receiving the DL grant on the secondary carrier; and
transmitting UL data on the secondary carrier after receiving the
UL grant on the primary carrier.
2. The method of claim 1, wherein the primary carrier is a licensed
carrier and the secondary carrier is an unlicensed carrier.
3. The method of claim 1, wherein the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are received by the UE on the secondary carrier and UL grants are
received by the UE on the primary carrier.
4. The method of claim 1, wherein the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are scheduled by self-scheduling on the secondary carrier and UL
grants are scheduled by cross-carrier scheduling on the primary
carrier.
5. The method of claim 1, further comprising: receiving information
about at least one of a set of downlink control information (DCI)
formats or DCI format sizes of respective DCI messages to monitor
on each subframe on each carrier; and monitoring for at least one
of the UL grant or the DL grant based on the information.
6. The method of claim 5, wherein each of the DCI format sizes of
the respective DCI messages is specific to a transmission mode.
7. The method of claim 1, further comprising: receiving information
on a number of blind decodes to perform per subframe; and blind
decoding based on the number of blind decodes to detect at least
one of the DL grant or the UL grant.
8. The method of claim 1, wherein the UL grant received on the
primary carrier corresponds to a plurality of unlicensed carriers,
and further comprising: selecting a carrier from among the
plurality of unlicensed carriers as the secondary carrier to
transmit the UL data.
9. The method of claim 8, wherein the selecting the carrier from
among the plurality of unlicensed carriers comprises: determining
channel availability of channels associated with the plurality of
unlicensed carriers, wherein a channel is available when an energy
of the channel is lower than an energy threshold; and selecting the
carrier associated with the channel for transmission of the UL data
based on at least one of the channel availability or a carrier
priority.
10. The method of claim 1, further comprising: receiving
configuration information from a serving base station adjusting a
number of resource blocks to monitor for receiving the UL grant;
and monitoring for the UL grant based on the received configuration
information adjusting the number of resource blocks to monitor for
receiving the UL grant.
11. A method for wireless communication by a base station,
comprising: sending a downlink (DL) grant for a secondary carrier
and an uplink (UL) grant for the secondary carrier, wherein the DL
grant is transmitted on the secondary carrier and the UL grant is
transmitted on a primary carrier; sending DL data on the secondary
carrier after sending the DL grant on the secondary carrier; and
receiving UL data on the secondary carrier after sending the UL
grant on the primary carrier.
12. The method of claim 11, wherein the primary carrier is a
licensed carrier, and the secondary carrier is an unlicensed
carrier.
13. The method of claim 11, wherein the DL grant and the UL grant
are transmitted from the base station using a configuration where
DL grants are communicated on the secondary carrier and UL grants
are communicated on the primary carrier.
14. The method of claim 11, wherein the DL grant and the UL grant
are transmitted from the base station using a configuration where
DL grants are scheduled by self-scheduling on the secondary carrier
and UL grants are scheduled by cross-carrier scheduling on the
primary carrier.
15. The method of claim 11, further comprising: sending information
about a set of downlink control information (DCI) formats or DCI
format sizes to monitor on each subframe on each carrier.
16. The method of claim 15, wherein each of the DCI format sizes is
specific to a transmission mode.
17. The method of claim 11, further comprising: sending
configuration information, indicating a maximum number of blind
decodes to be performed at a user equipment (UE) per subframe to
detect at least one of the DL grant or the UL grant.
18. The method of claim 11, further comprising selecting an UL/DL
grant configuration based on a time division duplex (TDD) subframe
configuration.
19. The method of claim 18, wherein the UL/DL grant configuration
includes sending DL grants on the secondary carrier and UL grants
on the primary carrier when the TDD subframe configuration includes
more UL subframes than DL subframes; and wherein the UL/DL grant
configuration includes sending DL grants on the secondary carrier
and UL grants on the secondary carrier when the TDD subframe
configuration includes more UL subframes than DL subframes.
20. The method of claim 11, wherein a scheduling mode is configured
independently for each of available carriers including the primary
carrier and the secondary carrier.
21. The method of claim 20, wherein the scheduling mode is
configured based on at least one of interference or channel
availability in each of the available carriers.
22. The method of claim 11, wherein a scheduling mode is configured
independently for each of available carriers including the primary
carrier and the secondary carrier, and independently for the UL
grant and the DL grant.
23. The method of claim 11, wherein the secondary carrier to
receive the UL data is a carrier selected among a plurality of
unlicensed carriers, and wherein the UL grant sent on the primary
carrier is specified for the plurality of unlicensed carriers.
24. The method of claim 23, wherein the base station is configured
to blindly detect the selected carrier.
25. The method of claim 11, further comprising: sending
configuration information adjusting a number of resources the UE is
to monitor for the UL grant.
26. The method of claim 25, further comprising: configuring a
number of candidates or aggregation levels to monitor in a physical
downlink control channel (PDCCH); configuring at least one of a
number of sets of enhanced PDCCHs (EPDCCHs), a number of resource
blocks (RBs) for each set of EPDCCHs, a type of EPDCCH, or a number
of candidates or aggregation levels for EPDCCH monitoring.
27. The method of claim 25, wherein the number of resources to
monitor depends on at least one of a time division duplex (TDD)
subframe configuration or a number of active unlicensed
carriers.
28. A user equipment (UE) for wireless communication, comprising:
means for receiving a downlink (DL) grant for a secondary carrier
and an uplink (UL) grant for the secondary carrier, wherein the DL
grant is received on the secondary carrier and the UL grant is
received on a primary carrier; means for receiving DL data on the
secondary carrier after receiving the DL grant on the secondary
carrier; and means for transmitting UL data on the secondary
carrier after receiving the UL grant on the primary carrier.
29. The UE of claim 28, wherein the primary carrier is a licensed
carrier and the secondary carrier is an unlicensed carrier.
30. The UE of claim 28, wherein the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are received by the UE on the secondary carrier and UL grants are
received by the UE on the primary carrier.
31. The UE of claim 28, wherein the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are scheduled by self-scheduling on the secondary carrier and UL
grants are scheduled by cross-carrier scheduling on the primary
carrier.
32. The UE of claim 28, further comprising: means for receiving
information about at least one of a set of downlink control
information (DCI) formats or DCI format sizes of respective DCI
messages to monitor on each subframe on each carrier; and means for
monitoring for at least one of the UL grant or the DL grant based
on the information.
33. The UE of claim 32, wherein each of the DCI format sizes of the
respective DCI messages is specific to a transmission mode.
34. The UE of claim 28, further comprising: means for receiving
information on a number of blind decodes to perform per subframe;
and means for blind decoding based on the number of blind decodes
to detect at least one of the DL grant or the UL grant.
35. The UE of claim 28, wherein the UL grant received on the
primary carrier corresponds to a plurality of unlicensed carriers,
and further comprising: means for selecting a carrier from among
the plurality of unlicensed carriers as the secondary carrier to
transmit the UL data.
36. The UE of claim 35, wherein the means for selecting the carrier
from among the plurality of unlicensed carriers is configured to:
determine channel availability of channels associated with the
plurality of unlicensed carriers, wherein a channel is available
when an energy of the channel is lower than an energy threshold;
and select the carrier associated with the channel for transmission
of the UL data based on at least one of the channel availability or
a carrier priority.
37. The UE of claim 28, further comprising: means for receiving
configuration information from a serving base station adjusting a
number of resource blocks to monitor for receiving the UL grant;
and means for monitoring for the UL grant based on the received
configuration information adjusting the number of resource blocks
to monitor for receiving the UL grant.
38. A base station for wireless communication, comprising: means
for sending a downlink (DL) grant for a secondary carrier and an
uplink (UL) grant for the secondary carrier, wherein the DL grant
is transmitted on the secondary carrier and the UL grant is
transmitted on a primary carrier; means for sending DL data on the
secondary carrier after sending the DL grant on the secondary
carrier; and means for receiving UL data on the secondary carrier
after sending the UL grant on the primary carrier.
39. The base station of claim 38, wherein the primary carrier is a
licensed carrier, and the secondary carrier is an unlicensed
carrier.
40. The base station of claim 38, wherein the DL grant and the UL
grant are transmitted from the base station using a configuration
where DL grants are communicated on the secondary carrier and UL
grants are communicated on the primary carrier.
41. The base station of claim 38, wherein the DL grant and the UL
grant are transmitted from the base station using a configuration
where DL grants are scheduled by self-scheduling on the secondary
carrier and UL grants are scheduled by cross-carrier scheduling on
the primary carrier.
42. The base station of claim 38, further comprising: means for
sending information about a set of downlink control information
(DCI) formats or DCI format sizes to monitor on each subframe on
each carrier.
43. The base station of claim 42, wherein each of the DCI format
sizes is specific to a transmission mode.
44. The base station of claim 38, further comprising: means for
sending configuration information, indicating a maximum number of
blind decodes to be performed at a user equipment (UE) per subframe
to detect at least one of the DL grant or the UL grant.
45. The base station of claim 38, further comprising: means for
selecting an UL/DL grant configuration based on a time division
duplex (TDD) subframe configuration.
46. The base station of claim 45, wherein the UL/DL grant
configuration includes sending DL grants on the secondary carrier
and UL grants on the primary carrier when the TDD subframe
configuration includes more UL subframes than DL subframes; and
wherein the UL/DL grant configuration includes sending DL grants on
the secondary carrier and UL grants on the secondary carrier when
the TDD subframe configuration includes more UL subframes than DL
subframes.
47. The base station of claim 38, wherein a scheduling mode is
configured independently for each of available carriers including
the primary carrier and the secondary carrier.
48. The base station of claim 47, wherein the scheduling mode is
configured based on at least one of interference or channel
availability in each of the available carriers.
49. The base station of claim 38, wherein a scheduling mode is
configured independently for each of available carriers including
the primary carrier and the secondary carrier, and independently
for the UL grant and the DL grant.
50. The base station of claim 38, wherein the secondary carrier to
receive the UL data is a carrier selected among a plurality of
unlicensed carriers, and wherein the UL grant sent on the primary
carrier is specified for the plurality of unlicensed carriers.
51. The base station of claim 50, wherein the base station is
configured to blindly detect the selected carrier.
52. The base station of claim 38, further comprising: means for
sending configuration information adjusting a number of resources
the UE is to monitor for the UL grant.
53. The base station of claim 52, further comprising: means for
configuring a number of candidates or aggregation levels to monitor
in a physical downlink control channel (PDCCH); means for
configuring at least one of a number of sets of enhanced PDCCHs
(EPDCCHs), a number of resource blocks (RBs) for each set of
EPDCCHs, a type of EPDCCH, or a number of candidates or aggregation
levels for EPDCCH monitoring.
54. The base station of claim 52, wherein the number of resources
to monitor depends on at least one of a time division duplex (TDD)
subframe configuration or a number of active unlicensed
carriers.
55. A user equipment (UE) for wireless communication, comprising: a
memory; and at least one processor coupled to the memory and
configured to: receive a downlink (DL) grant for a secondary
carrier and an uplink (UL) grant for the secondary carrier, wherein
the DL grant is received on the secondary carrier and the UL grant
is received on a primary carrier; receive DL data on the secondary
carrier after receiving the DL grant on the secondary carrier; and
transmit UL data on the secondary carrier after receiving the UL
grant on the primary carrier.
56. The UE of claim 55, wherein the primary carrier is a licensed
carrier and the secondary carrier is an unlicensed carrier.
57. The UE of claim 55, wherein the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are received by the UE on the secondary carrier and UL grants are
received by the UE on the primary carrier.
58. The UE of claim 55, wherein the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are scheduled by self-scheduling on the secondary carrier and UL
grants are scheduled by cross-carrier scheduling on the primary
carrier.
59. The UE of claim 55, wherein the at least one processor is
further configured to: receive information about at least one of a
set of downlink control information (DCI) formats or DCI format
sizes of respective DCI messages to monitor on each subframe on
each carrier; and monitor for at least one of the UL grant or the
DL grant based on the information.
60. The UE of claim 59, wherein each of the DCI format sizes of the
respective DCI messages is specific to a transmission mode.
61. The UE of claim 55, wherein the at least one processor is
further configured to: receive information on a number of blind
decodes to perform per subframe; and blind decode based on the
number of blind decodes to detect at least one of the DL grant or
the UL grant.
62. The UE of claim 55, wherein the UL grant received on the
primary carrier corresponds to a plurality of unlicensed carriers,
and the at least one processor is further configured to: select a
carrier from among the plurality of unlicensed carriers as the
secondary carrier to transmit the UL data.
63. The UE of claim 62, wherein the at least one processor
configured to select the carrier from among the plurality of
unlicensed carriers is configured to: determine channel
availability of channels associated with the plurality of
unlicensed carriers, wherein a channel is available when an energy
of the channel is lower than an energy threshold; and select the
carrier associated with the channel for transmission of the UL data
based on at least one of the channel availability or a carrier
priority.
64. The UE of claim 55, wherein the at least one processor is
further configured to: receive configuration information from a
serving base station adjusting a number of resource blocks to
monitor for receiving the UL grant; and monitor for the UL grant
based on the received configuration information adjusting the
number of resource blocks to monitor for receiving the UL
grant.
65. A base station for wireless communication, comprising: a
memory; and at least one processor coupled to the memory and
configured to: send a downlink (DL) grant for a secondary carrier
and an uplink (UL) grant for the secondary carrier, wherein the DL
grant is transmitted on the secondary carrier and the UL grant is
transmitted on a primary carrier; send DL data on the secondary
carrier after sending the DL grant on the secondary carrier; and
receive UL data on the secondary carrier after sending the UL grant
on the primary carrier.
66. The base station of claim 65, wherein the primary carrier is a
licensed carrier, and the secondary carrier is an unlicensed
carrier.
67. The base station of claim 65, wherein the DL grant and the UL
grant are transmitted from the base station using a configuration
where DL grants are communicated on the secondary carrier and UL
grants are communicated on the primary carrier.
68. The base station of claim 65, wherein the DL grant and the UL
grant are transmitted from the base station using a configuration
where DL grants are scheduled by self-scheduling on the secondary
carrier and UL grants are scheduled by cross-carrier scheduling on
the primary carrier.
69. The base station of claim 65, wherein the at least one
processor is further configured to: send information about a set of
downlink control information (DCI) formats or DCI format sizes to
monitor on each subframe on each carrier.
70. The base station of claim 69, wherein each of the DCI format
sizes is specific to a transmission mode.
71. The base station of claim 65, wherein the at least one
processor is further configured to: send configuration information,
indicating a maximum number of blind decodes to be performed at a
user equipment (UE) per subframe to detect at least one of the DL
grant or the UL grant.
72. The base station of claim 65, wherein the at least one
processor is further configured to: select an UL/DL grant
configuration based on a time division duplex (TDD) subframe
configuration.
73. The base station of claim 72, wherein the UL/DL grant
configuration includes sending DL grants on the secondary carrier
and UL grants on the primary carrier when the TDD subframe
configuration includes more UL subframes than DL subframes; and
wherein the UL/DL grant configuration includes sending DL grants on
the secondary carrier and UL grants on the secondary carrier when
the TDD subframe configuration includes more UL subframes than DL
subframes.
74. The base station of claim 65, wherein a scheduling mode is
configured independently for each of available carriers including
the primary carrier and the secondary carrier.
75. The base station of claim 74, wherein the scheduling mode is
configured based on at least one of interference or channel
availability in each of the available carriers.
76. The base station of claim 65, wherein a scheduling mode is
configured independently for each of available carriers including
the primary carrier and the secondary carrier, and independently
for the UL grant and the DL grant.
77. The base station of claim 65, wherein the secondary carrier to
receive the UL data is a carrier selected among a plurality of
unlicensed carriers, and wherein the UL grant sent on the primary
carrier is specified for the plurality of unlicensed carriers.
78. The base station of claim 77, wherein the base station is
configured to blindly detect the selected carrier.
79. The base station of claim 65, wherein the at least one
processor is further configured to: send configuration information
adjusting a number of resources the UE is to monitor for the UL
grant.
80. The base station of claim 79, wherein the at least one
processor is further configured to: configure a number of
candidates or aggregation levels to monitor in a physical downlink
control channel (PDCCH); configure at least one of a number of sets
of enhanced PDCCHs (EPDCCHs), a number of resource blocks (RBs) for
each set of EPDCCHs, a type of EPDCCH, or a number of candidates or
aggregation levels for EPDCCH monitoring.
81. The base station of claim 79, wherein the number of resources
to monitor depends on at least one of a time division duplex (TDD)
subframe configuration or a number of active unlicensed
carriers.
82. A computer-readable medium storing computer executable code for
wireless communication by a user equipment (UE), comprising code
to: receive a downlink (DL) grant for a secondary carrier and an
uplink (UL) grant for the secondary carrier, wherein the DL grant
is received on the secondary carrier and the UL grant is received
on a primary carrier; receive DL data on the secondary carrier
after receiving the DL grant on the secondary carrier; and transmit
UL data on the secondary carrier after receiving the UL grant on
the primary carrier.
83. The computer-readable medium of claim 82, wherein the primary
carrier is a licensed carrier and the secondary carrier is an
unlicensed carrier.
84. The computer-readable medium of claim 82, wherein the DL grant
and the UL grant are received from a base station using a
configuration where DL grants are received by the UE on the
secondary carrier and UL grants are received by the UE on the
primary carrier.
85. The computer-readable medium of claim 82, wherein the DL grant
and the UL grant are received from a base station using a
configuration where DL grants are scheduled by self-scheduling on
the secondary carrier and UL grants are scheduled by cross-carrier
scheduling on the primary carrier.
86. The computer-readable medium of claim 82, further comprising
code to: receive information about at least one of a set of
downlink control information (DCI) formats or DCI format sizes of
respective DCI messages to monitor on each subframe on each
carrier; and monitor for at least one of the UL grant or the DL
grant based on the information.
87. The computer-readable medium of claim 86, wherein each of the
DCI format sizes of the respective DCI messages is specific to a
transmission mode.
88. The computer-readable medium of claim 82, further comprising
code to: receive information on a number of blind decodes to
perform per subframe; and blind decode based on the number of blind
decodes to detect at least one of the DL grant or the UL grant.
89. The computer-readable medium of claim 82, wherein the UL grant
received on the primary carrier corresponds to a plurality of
unlicensed carriers, further comprising code to: select a carrier
from among the plurality of unlicensed carriers as the secondary
carrier to transmit the UL data.
90. The computer-readable medium of claim 89, wherein the code to
select the carrier from among the plurality of unlicensed carriers
comprises code to: determine channel availability of channels
associated with the plurality of unlicensed carriers, wherein a
channel is available when an energy of the channel is lower than an
energy threshold; and select the carrier associated with the
channel for transmission of the UL data based on at least one of
the channel availability or a carrier priority.
91. The computer-readable medium of claim 82, further comprising
code to: receive configuration information from a serving base
station adjusting a number of resource blocks to monitor for
receiving the UL grant; and monitor for the UL grant based on the
received configuration information adjusting the number of resource
blocks to monitor for receiving the UL grant.
92. A computer-readable medium storing computer executable code for
wireless communication by a base station, comprising code to: send
a downlink (DL) grant for a secondary carrier and an uplink (UL)
grant for the secondary carrier, wherein the DL grant is
transmitted on the secondary carrier and the UL grant is
transmitted on a primary carrier; send DL data on the secondary
carrier after sending the DL grant on the secondary carrier; and
receive UL data on the secondary carrier after sending the UL grant
on the primary carrier.
93. The computer-readable medium of claim 92, wherein the primary
carrier is a licensed carrier, and the secondary carrier is an
unlicensed carrier.
94. The computer-readable medium of claim 92, wherein the DL grant
and the UL grant are transmitted from the base station using a
configuration where DL grants are communicated on the secondary
carrier and UL grants are communicated on the primary carrier.
95. The computer-readable medium of claim 92, wherein the DL grant
and the UL grant are transmitted from the base station using a
configuration where DL grants are scheduled by self-scheduling on
the secondary carrier and UL grants are scheduled by cross-carrier
scheduling on the primary carrier.
96. The computer-readable medium of claim 92, further comprising
code to: send information about a set of downlink control
information (DCI) formats or DCI format sizes to monitor on each
subframe on each carrier.
97. The computer-readable medium of claim 96, wherein each of the
DCI format sizes is specific to a transmission mode.
98. The computer-readable medium of claim 92, further comprising
code to: send configuration information, indicating a maximum
number of blind decodes to be performed at a user equipment (UE)
per subframe to detect at least one of the DL grant or the UL
grant.
99. The computer-readable medium of claim 92, further comprising
code to select an UL/DL grant configuration based on a time
division duplex (TDD) subframe configuration.
100. The computer-readable medium of claim 99, wherein the UL/DL
grant configuration includes sending DL grants on the secondary
carrier and UL grants on the primary carrier when the TDD subframe
configuration includes more UL subframes than DL subframes; and
wherein the UL/DL grant configuration includes sending DL grants on
the secondary carrier and UL grants on the secondary carrier when
the TDD subframe configuration includes more UL subframes than DL
subframes.
101. The computer-readable medium of claim 92, wherein a scheduling
mode is configured independently for each of available carriers
including the primary carrier and the secondary carrier.
102. The computer-readable medium of claim 101, wherein the
scheduling mode is configured based on at least one of interference
or channel availability in each of the available carriers.
103. The computer-readable medium of claim 92, wherein a scheduling
mode is configured independently for each of available carriers
including the primary carrier and the secondary carrier, and
independently for the UL grant and the DL grant.
104. The computer-readable medium of claim 92, wherein the
secondary carrier to receive the UL data is a carrier selected
among a plurality of unlicensed carriers, and wherein the UL grant
sent on the primary carrier is specified for the plurality of
unlicensed carriers.
105. The computer-readable medium of claim 104, wherein the base
station is configured to blindly detect the selected carrier.
106. The computer-readable medium of claim 92, further comprising
code to: send configuration information adjusting a number of
resources the UE is to monitor for the UL grant.
107. The computer-readable medium of claim 106, further comprising
code to: configure a number of candidates or aggregation levels to
monitor in a physical downlink control channel (PDCCH); configure
at least one of a number of sets of enhanced PDCCHs (EPDCCHs), a
number of resource blocks (RBs) for each set of EPDCCHs, a type of
EPDCCH, or a number of candidates or aggregation levels for EPDCCH
monitoring.
108. The computer-readable medium of claim 106, wherein the number
of resources to monitor depends on at least one of a time division
duplex (TDD) subframe configuration or a number of active
unlicensed carriers.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 62/134,487 entitled "Scheduling enhancements
for LTE-U" and filed on Mar. 17, 2015, which is expressly
incorporated by reference herein in its entirety.
BACKGROUND
[0002] 1. Field
[0003] The present disclosure relates generally to communication
systems, and more particularly, to mitigation of inter-base station
resynchronization loss in long term evolution (LTE)/LTE-Advanced
(LTE-A) networks operating in contention-based shared frequency
spectrum.
[0004] 2. Background
[0005] Wireless communication systems are widely deployed to
provide various telecommunication services such as telephony,
video, data, messaging, and broadcasts. Typical wireless
communication systems may employ multiple-access technologies
capable of supporting communication with multiple users by sharing
available system resources. Examples of such multiple-access
technologies include code division multiple access (CDMA) systems,
time division multiple access (TDMA) systems, frequency division
multiple access (FDMA) systems, orthogonal frequency division
multiple access (OFDMA) systems, single-carrier frequency division
multiple access (SC-FDMA) systems, and time division synchronous
code division multiple access (TD-SCDMA) systems.
[0006] These multiple access technologies have been adopted in
various telecommunication standards to provide a common protocol
that enables different wireless devices to communicate on a
municipal, national, regional, and even global level. An example
telecommunication standard is Long Term Evolution (LTE). LTE is a
set of enhancements to the Universal Mobile Telecommunications
System (UMTS) mobile standard promulgated by Third Generation
Partnership Project (3GPP). LTE is designed to support mobile
broadband access through improved spectral efficiency, lowered
costs, and improved services using OFDMA on the downlink, SC-FDMA
on the uplink, and multiple-input multiple-output (MIMO) antenna
technology. However, as the demand for mobile broadband access
continues to increase, there exists a need for further improvements
in LTE technology. These improvements may also be applicable to
other multi-access technologies and the telecommunication standards
that employ these technologies.
[0007] Some modes of communication may enable communications
between a base station and a UE over a contention-based shared
radio frequency spectrum band, or over different radio frequency
spectrum bands (e.g., a licensed radio frequency spectrum band or
an unlicensed radio frequency spectrum band) of a cellular network.
With increasing data traffic in cellular networks that use a
licensed radio frequency spectrum band, offloading of at least some
data traffic to an unlicensed radio frequency spectrum band may
provide a cellular operator with opportunities for enhanced data
transmission capacity. An unlicensed radio frequency spectrum band
may also provide service in areas where access to a licensed radio
frequency spectrum band is unavailable. When utilizing an
unlicensed carrier, channel availability may be uncertain. Thus,
several difficulties may arise due to the uncertainty of channel
availability when an unlicensed carrier is used.
SUMMARY
[0008] The following presents a simplified summary of one or more
aspects in order to provide a basic understanding of such aspects.
This summary is not an extensive overview of all contemplated
aspects, and is intended to neither identify key or critical
elements of all aspects nor delineate the scope of any or all
aspects. Its sole purpose is to present some concepts of one or
more aspects in a simplified form as a prelude to the more detailed
description that is presented later.
[0009] Channel availability is uncertain when employing an
unlicensed carrier. In particular, scheduling grants in advance may
be difficult because of the uncertainty associated with future
channels availability. Accordingly, scheduling uplink (UL) and/or
downlink (DL) grants exclusively using self-scheduling or
exclusively using cross-carrier scheduling for utilizing an
unlicensed carrier may result in wasted communication
opportunities. Aspects disclosed herein whereby an eNodeB (eNB) may
use licensed and unlicensed carriers to communicate downlink grants
and uplink grants for an unlicensed carrier to a UE.
[0010] In one aspect of the present disclosure, a method of
wireless communication by a user equipment (UE) includes receiving
a DL grant for a secondary carrier and an UL grant for the
secondary carrier. In an aspect, the DL grant is received on the
secondary carrier and the UL grant is received on a primary
carrier. The method further includes receiving DL data on the
secondary carrier after receiving the DL grant on the secondary
carrier. The method further includes transmitting UL data on the
secondary carrier after receiving the UL grant on the primary
carrier.
[0011] In an aspect, a UE includes means for receiving a downlink
(DL) grant for a secondary carrier and an uplink (UL) grant for the
secondary carrier, where the DL grant is received on the secondary
carrier and the UL grant is received on a primary carrier. The UE
further includes means for receiving DL data on the secondary
carrier after receiving the DL grant on the secondary carrier. The
UE further includes means for transmitting UL data on the secondary
carrier after receiving the UL grant on the primary carrier.
[0012] In an aspect, a UE includes a memory and at least one
processor coupled to the memory. The at least one processor is
configured to: receive a downlink (DL) grant for a secondary
carrier and an uplink (UL) grant for the secondary carrier, where
the DL grant is received on the secondary carrier and the UL grant
is received on a primary carrier, receive DL data on the secondary
carrier after receiving the DL grant on the secondary carrier, and
transmit UL data on the secondary carrier after receiving the UL
grant on the primary carrier.
[0013] In an aspect, a computer-readable medium stores computer
executable code for wireless communication by a UE. The
computer-readable medium includes code to: receive a downlink (DL)
grant for a secondary carrier and an uplink (UL) grant for the
secondary carrier, where the DL grant is received on the secondary
carrier and the UL grant is received on a primary carrier, receive
DL data on the secondary carrier after receiving the DL grant on
the secondary carrier, and transmit UL data on the secondary
carrier after receiving the UL grant on the primary carrier. In an
aspect, the computer-readable medium may be a non-transitory
computer-readable medium.
[0014] In another aspect of the present disclosure, a method of
wireless communication by a base station includes sending a DL
grant for a secondary carrier and a UL grant for the secondary
carrier. In an aspect, the DL grant is transmitted on the secondary
carrier and the UL grant is transmitted on a primary carrier. The
method further includes sending DL data on the secondary carrier
after sending the DL grant on the secondary carrier. The method
further includes receiving UL data on the secondary carrier after
sending the UL grant on the primary carrier.
[0015] In an aspect, a UE includes means for sending a DL grant for
a secondary carrier and a UL grant for the secondary carrier, where
the DL grant is transmitted on the secondary carrier and the UL
grant is transmitted on a primary carrier. The UE further includes
means for sending DL data on the secondary carrier after sending
the DL grant on the secondary carrier. The UE further includes
means for receiving UL data on the secondary carrier after sending
the UL grant on the primary carrier.
[0016] In an aspect, a UE includes a memory and at least one
processor coupled to the memory. The at least one processor is
configured to: send a DL grant for a secondary carrier and a UL
grant for the secondary carrier, where the DL grant is transmitted
on the secondary carrier and the UL grant is transmitted on a
primary carrier, send DL data on the secondary carrier after
sending the DL grant on the secondary carrier, and receive UL data
on the secondary carrier after sending the UL grant on the primary
carrier.
[0017] In an aspect, a computer-readable medium stores computer
executable code for wireless communication by a UE. The
computer-readable medium includes code to: send a DL grant for a
secondary carrier and a UL grant for the secondary carrier, where
the DL grant is transmitted on the secondary carrier and the UL
grant is transmitted on a primary carrier, send DL data on the
secondary carrier after sending the DL grant on the secondary
carrier, and receive UL data on the secondary carrier after sending
the UL grant on the primary carrier. In an aspect, the
computer-readable medium may be a non-transitory computer-readable
medium.
[0018] To the accomplishment of the foregoing and related ends, the
one or more aspects comprise the features hereinafter fully
described and particularly pointed out in the claims. The following
description and the annexed drawings set forth in detail certain
illustrative features of the one or more aspects. These features
are indicative, however, of but a few of the various ways in which
the principles of various aspects may be employed, and this
description is intended to include all such aspects and their
equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a diagram illustrating an example of a wireless
communications system and an access network.
[0020] FIGS. 2A, 2B, 2C, and 2D are diagrams illustrating LTE
examples of a DL frame structure, DL channels within the DL frame
structure, an UL frame structure, and UL channels within the UL
frame structure, respectively.
[0021] FIG. 3 is a diagram illustrating an example of an evolved
Node B (eNB) and user equipment (UE) in an access network.
[0022] FIG. 4 is an illustration of an example of a wireless
communication over an unlicensed radio frequency spectrum band, in
accordance with various aspects of the present disclosure.
[0023] FIG. 5A illustrates an example diagram of a self-scheduling
mode.
[0024] FIG. 5B illustrates an example diagram of a cross-carrier
scheduling mode.
[0025] FIG. 6A and FIG. 6B are example diagrams illustrating uses
of a primary serving cell served by a PCC and a secondary serving
cell served by an SCC for uplink communication.
[0026] FIG. 7 is an example diagram illustrating self-scheduling
and cross-carrier scheduling according to an aspect of the
disclosure.
[0027] FIG. 8 is a flow chart of a method of wireless
communication.
[0028] FIG. 9A is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 11, according
to an aspect of the disclosure.
[0029] FIG. 9B is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 11, according
to an aspect of the disclosure.
[0030] FIG. 10A is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 11, according
to an aspect of the disclosure.
[0031] FIG. 10B is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 11, according
to an aspect of the disclosure.
[0032] FIG. 11 is a conceptual data flow diagram illustrating the
data flow between different means/components in an exemplary
apparatus.
[0033] FIG. 12 is a diagram illustrating an example of a hardware
implementation for an apparatus employing a processing system.
[0034] FIG. 13 is a flow chart of a method of wireless
communication.
[0035] FIG. 14A is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 16, according
to an aspect of the disclosure.
[0036] FIG. 14B is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 16, according
to an aspect of the disclosure.
[0037] FIG. 15A is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 16, according
to an aspect of the disclosure.
[0038] FIG. 15B is a flow chart of a method of wireless
communication expanding from the flow chart of FIG. 16, according
to an aspect of the disclosure.
[0039] FIG. 16 is a conceptual data flow diagram illustrating the
data flow between different means/components in an exemplary
apparatus.
[0040] FIG. 17 is a diagram illustrating an example of a hardware
implementation for an apparatus employing a processing system.
DETAILED DESCRIPTION
[0041] The detailed description set forth below in connection with
the appended drawings is intended as a description of various
configurations and is not intended to represent the only
configurations in which the concepts described herein may be
practiced. The detailed description includes specific details for
the purpose of providing a thorough understanding of various
concepts. However, it will be apparent to those skilled in the art
that these concepts may be practiced without these specific
details. In some instances, well known structures and components
are shown in block diagram form in order to avoid obscuring such
concepts.
[0042] Several aspects of telecommunication systems will now be
presented with reference to various apparatus and methods. These
apparatus and methods will be described in the following detailed
description and illustrated in the accompanying drawings by various
blocks, components, circuits, processes, algorithms, etc.
(collectively referred to as "elements"). These elements may be
implemented using electronic hardware, computer software, or any
combination thereof. Whether such elements are implemented as
hardware or software depends upon the particular application and
design constraints imposed on the overall system.
[0043] By way of example, an element, or any portion of an element,
or any combination of elements may be implemented as a "processing
system" that includes one or more processors. Examples of
processors include microprocessors, microcontrollers, graphics
processing units (GPUs), central processing units (CPUs),
application processors, digital signal processors (DSPs), reduced
instruction set computing (RISC) processors, systems on a chip
(SoC), baseband processors, field programmable gate arrays (FPGAs),
programmable logic devices (PLDs), state machines, gated logic,
discrete hardware circuits, and other suitable hardware configured
to perform the various functionality described throughout this
disclosure. One or more processors in the processing system may
execute software. Software shall be construed broadly to mean
instructions, instruction sets, code, code segments, program code,
programs, subprograms, software components, applications, software
applications, software packages, routines, subroutines, objects,
executables, threads of execution, procedures, functions, etc.,
whether referred to as software, firmware, middleware, microcode,
hardware description language, or otherwise.
[0044] Accordingly, in one or more example embodiments, the
functions described may be implemented in hardware, software, or
any combination thereof. If implemented in software, the functions
may be stored on or encoded as one or more instructions or code on
a computer-readable medium. Computer-readable media includes
computer storage media. Storage media may be any available media
that can be accessed by a computer. By way of example, and not
limitation, such computer-readable media can comprise a
random-access memory (RAM), a read-only memory (ROM), an
electrically erasable programmable ROM (EEPROM), optical disk
storage, magnetic disk storage, other magnetic storage devices,
combinations of the aforementioned types of computer-readable
media, or any other medium that can be used to store computer
executable code in the form of instructions or data structures that
can be accessed by a computer.
[0045] FIG. 1 is a diagram illustrating an example of a wireless
communications system and an access network 100. The wireless
communications system (also referred to as a wireless wide area
network (WWAN)) includes base stations 102, UEs 104, and an Evolved
Packet Core (EPC) 160. The base stations 102 may include macro
cells (high power cellular base station) and/or small cells (low
power cellular base station). The macro cells include eNBs. The
small cells include femtocells, picocells, and microcells.
[0046] The base stations 102 (collectively referred to as Evolved
Universal Mobile Telecommunications System (UMTS) Terrestrial Radio
Access Network (E-UTRAN)) interface with the EPC 160 through
backhaul links 132 (e.g., 51 interface). In addition to other
functions, the base stations 102 may perform one or more of the
following functions: transfer of user data, radio channel ciphering
and deciphering, integrity protection, header compression, mobility
control functions (e.g., handover, dual connectivity), inter-cell
interference coordination, connection setup and release, load
balancing, distribution for non-access stratum (NAS) messages, NAS
node selection, synchronization, radio access network (RAN)
sharing, multimedia broadcast multicast service (MBMS), subscriber
and equipment trace, RAN information management (RIM), paging,
positioning, and delivery of warning messages. The base stations
102 may communicate directly or indirectly (e.g., through the EPC
160) with each other over backhaul links 134 (e.g., X2 interface).
The backhaul links 134 may be wired or wireless.
[0047] The base stations 102 may wirelessly communicate with the
UEs 104. Each of the base stations 102 may provide communication
coverage for a respective geographic coverage area 110. There may
be overlapping geographic coverage areas 110. For example, the
small cell 102' may have a coverage area 110' that overlaps the
coverage area 110 of one or more macro base stations 102. A network
that includes both small cell and macro cells may be known as a
heterogeneous network. A heterogeneous network may also include
Home Evolved Node Bs (eNBs) (HeNBs), which may provide service to a
restricted group known as a closed subscriber group (CSG). The
communication links 120 between the base stations 102 and the UEs
104 may include uplink (UL) (also referred to as reverse link)
transmissions from a UE 104 to a base station 102 and/or downlink
(DL) (also referred to as forward link) transmissions from a base
station 102 to a UE 104. The communication links 120 may use MIMO
antenna technology, including spatial multiplexing, beamforming,
and/or transmit diversity. The communication links may be through
one or more carriers. The base stations 102/UEs 104 may use
spectrum up to Y MHz (e.g., 5, 10, 15, 20 MHz) bandwidth per
carrier allocated in a carrier aggregation of up to a total of Yx
MHz (x component carriers) used for transmission in each direction.
The carriers may or may not be adjacent to each other. Allocation
of carriers may be asymmetric with respect to DL and UL (e.g., more
or less carriers may be allocated for DL than for UL). The
component carriers may include a primary component carrier and one
or more secondary component carriers. A primary component carrier
may be referred to as a primary cell (PCell) and a secondary
component carrier may be referred to as a secondary cell
(SCell).
[0048] The wireless communications system may further include a
Wi-Fi access point (AP) 150 in communication with Wi-Fi stations
(STAs) 152 via communication links 154 in a 5 GHz unlicensed
frequency spectrum. When communicating in an unlicensed frequency
spectrum, the STAs 152/AP 150 may perform a clear channel
assessment (CCA) prior to communicating in order to determine
whether the channel is available.
[0049] The small cell 102' may operate in a licensed and/or an
unlicensed frequency spectrum. When operating in an unlicensed
frequency spectrum, the small cell 102' may employ LTE and use the
same 5 GHz unlicensed frequency spectrum as used by the Wi-Fi AP
150. The small cell 102', employing LTE in an unlicensed frequency
spectrum, may boost coverage to and/or increase capacity of the
access network. LTE in an unlicensed spectrum may be referred to as
LTE-unlicensed (LTE-U), licensed assisted access (LAA), or
MuLTEfire.
[0050] The EPC 160 may include a Mobility Management Entity (MME)
162, other MMEs 164, a Serving Gateway 166, a Multimedia Broadcast
Multicast Service (MBMS) Gateway 168, a Broadcast Multicast Service
Center (BM-SC) 170, and a Packet Data Network (PDN) Gateway 172.
The MME 162 may be in communication with a Home Subscriber Server
(HSS) 174. The MME 162 is the control node that processes the
signaling between the UEs 104 and the EPC 160. Generally, the MME
162 provides bearer and connection management. All user Internet
protocol (IP) packets are transferred through the Serving Gateway
166, which itself is connected to the PDN Gateway 172. The PDN
Gateway 172 provides UE IP address allocation as well as other
functions. The PDN Gateway 172 and the BM-SC 170 are connected to
the IP Services 176. The IP Services 176 may include the Internet,
an intranet, an IP Multimedia Subsystem (IMS), a PS Streaming
Service (PSS), and/or other IP services. The BM-SC 170 may provide
functions for MBMS user service provisioning and delivery. The
BM-SC 170 may serve as an entry point for content provider MBMS
transmission, may be used to authorize and initiate MBMS Bearer
Services within a public land mobile network (PLMN), and may be
used to schedule MBMS transmissions. The MBMS Gateway 168 may be
used to distribute MBMS traffic to the base stations 102 belonging
to a Multicast Broadcast Single Frequency Network (MBSFN) area
broadcasting a particular service, and may be responsible for
session management (start/stop) and for collecting eMBMS related
charging information.
[0051] The base station may also be referred to as a Node B,
evolved Node B (eNB), an access point, a base transceiver station,
a radio base station, a radio transceiver, a transceiver function,
a basic service set (BSS), an extended service set (ESS), or some
other suitable terminology. The base station 102 provides an access
point to the EPC 160 for a UE 104. Examples of UEs 104 include a
cellular phone, a smart phone, a session initiation protocol (SIP)
phone, a laptop, a personal digital assistant (PDA), a satellite
radio, a global positioning system, a multimedia device, a video
device, a digital audio player (e.g., MP3 player), a camera, a game
console, a tablet, a smart device, a wearable device, or any other
similar functioning device. The UE 104 may also be referred to as a
station, a mobile station, a subscriber station, a mobile unit, a
subscriber unit, a wireless unit, a remote unit, a mobile device, a
wireless device, a wireless communications device, a remote device,
a mobile subscriber station, an access terminal, a mobile terminal,
a wireless terminal, a remote terminal, a handset, a user agent, a
mobile client, a client, or some other suitable terminology.
[0052] Referring again to FIG. 1, in certain aspects, the UE 104
may receive, on an unlicensed carrier, downlink grants from the eNB
102 for downlink communication on the unlicensed carrier, and may
receive, on a licensed carrier, uplink grants from the eNB 102 for
uplink communication on the unlicensed carrier (198).
[0053] FIG. 2A is a diagram 200 illustrating an example of a DL
frame structure in LTE.
[0054] FIG. 2B is a diagram 230 illustrating an example of channels
within the DL frame structure in LTE. FIG. 2C is a diagram 250
illustrating an example of an UL frame structure in LTE. FIG. 2D is
a diagram 280 illustrating an example of channels within the UL
frame structure in LTE. Other wireless communication technologies
may have a different frame structure and/or different channels. In
LTE, a frame (10 ms) may be divided into 10 equally sized
subframes. Each subframe may include two consecutive time slots. A
resource grid may be used to represent the two time slots, each
time slot including one or more time concurrent resource blocks
(RBs) (also referred to as physical RBs (PRBs)). The resource grid
is divided into multiple resource elements (REs). In LTE, for a
normal cyclic prefix, an RB contains 12 consecutive subcarriers in
the frequency domain and 7 consecutive symbols (for DL, OFDM
symbols; for UL, SC-FDMA symbols) in the time domain, for a total
of 84 REs. For an extended cyclic prefix, an RB contains 12
consecutive subcarriers in the frequency domain and 6 consecutive
symbols in the time domain, for a total of 72 REs. The number of
bits carried by each RE depends on the modulation scheme.
[0055] As illustrated in FIG. 2A, some of the REs carry DL
reference (pilot) signals (DL-RS) for channel estimation at the UE.
The DL-RS may include cell-specific reference signals (CRS) (also
sometimes called common RS), UE-specific reference signals (UE-RS),
and channel state information reference signals (CSI-RS). FIG. 2A
illustrates CRS for antenna ports 0, 1, 2, and 3 (indicated as
R.sub.0, R.sub.1, R.sub.2, and R.sub.3, respectively), UE-RS for
antenna port 5 (indicated as R.sub.5), and CSI-RS for antenna port
15 (indicated as R). FIG. 2B illustrates an example of various
channels within a DL subframe of a frame. The physical control
format indicator channel (PCFICH) is within symbol 0 of slot 0, and
carries a control format indicator (CFI) that indicates whether the
physical downlink control channel (PDCCH) occupies 1, 2, or 3
symbols (FIG. 2B illustrates a PDCCH that occupies 3 symbols). The
PDCCH carries downlink control information (DCI) within one or more
control channel elements (CCEs), each CCE including nine RE groups
(REGs), each REG including four consecutive REs in an OFDM symbol.
A UE may be configured with a UE-specific enhanced PDCCH (ePDCCH)
that also carries DCI. The ePDCCH may have 2, 4, or 8 RB pairs
(FIG. 2B shows two RB pairs, each subset including one RB pair).
The physical hybrid automatic repeat request (ARQ) (HARQ) indicator
channel (PHICH) is also within symbol 0 of slot 0 and carries the
HARQ indicator (HI) that indicates HARQ acknowledgement
(ACK)/negative ACK (NACK) feedback based on the physical uplink
shared channel (PUSCH). The primary synchronization channel (PSCH)
is within symbol 6 of slot 0 within subframes 0 and 5 of a frame,
and carries a primary synchronization signal (PSS) that is used by
a UE to determine subframe timing and a physical layer identity.
The secondary synchronization channel (SSCH) is within symbol 5 of
slot 0 within subframes 0 and 5 of a frame, and carries a secondary
synchronization signal (SSS) that is used by a UE to determine a
physical layer cell identity group number. Based on the physical
layer identity and the physical layer cell identity group number,
the UE can determine a physical cell identifier (PCI). Based on the
PCI, the UE can determine the locations of the aforementioned
DL-RS. The physical broadcast channel (PBCH) is within symbols 0,
1, 2 3, of slot 1 of subframe 0 of a frame, and carries a master
information block (MIB). The MIB provides a number of RBs in the DL
system bandwidth, a PHICH configuration, and a system frame number
(SFN). The physical downlink shared channel (PDSCH) carries user
data, broadcast system information not transmitted through the PBCH
such as system information blocks (SIBs), and paging messages.
[0056] As illustrated in FIG. 2C, some of the REs carry
demodulation reference signals (DM-RS) for channel estimation at
the eNB. The UE may additionally transmit sounding reference
signals (SRS) in the last symbol of a subframe. The SRS may have a
comb structure, and a UE may transmit SRS on one of the combs. The
SRS may be used by an eNB for channel quality estimation to enable
frequency-dependent scheduling on the UL. FIG. 2D illustrates an
example of various channels within an UL subframe of a frame. A
physical random access channel (PRACH) may be within one or more
subframes within a frame based on the PRACH configuration. The
PRACH may include six consecutive RB pairs within a subframe. The
PRACH allows the UE to perform initial system access and achieve UL
synchronization. A physical uplink control channel (PUCCH) may be
located on edges of the UL system bandwidth. The PUCCH carries
uplink control information (UCI), such as scheduling requests, a
channel quality indicator (CQI), a precoding matrix indicator
(PMI), a rank indicator (RI), and HARQ ACK/NACK feedback. The PUSCH
carries data, and may additionally be used to carry a buffer status
report (BSR), a power headroom report (PHR), and/or UCI.
[0057] FIG. 3 is a block diagram of an eNB 310 in communication
with a UE 350 in an access network. In the DL, IP packets from the
EPC 160 may be provided to a controller/processor 375. The
controller/processor 375 implements layer 3 and layer 2
functionality. Layer 3 includes a radio resource control (RRC)
layer, and layer 2 includes a packet data convergence protocol
(PDCP) layer, a radio link control (RLC) layer, and a medium access
control (MAC) layer. The controller/processor 375 provides RRC
layer functionality associated with broadcasting of system
information (e.g., MIB, SIBs), RRC connection control (e.g., RRC
connection paging, RRC connection establishment, RRC connection
modification, and RRC connection release), inter radio access
technology (RAT) mobility, and measurement configuration for UE
measurement reporting; PDCP layer functionality associated with
header compression/decompression, security (ciphering, deciphering,
integrity protection, integrity verification), and handover support
functions; RLC layer functionality associated with the transfer of
upper layer packet data units (PDUs), error correction through ARQ,
concatenation, segmentation, and reassembly of RLC service data
units (SDUs), re-segmentation of RLC data PDUs, and reordering of
RLC data PDUs; and MAC layer functionality associated with mapping
between logical channels and transport channels, multiplexing of
MAC SDUs onto transport blocks (TBs), demuliplexing of MAC SDUs
from TBs, scheduling information reporting, error correction
through HARQ, priority handling, and logical channel
prioritization.
[0058] The transmit (TX) processor 316 and the receive (RX)
processor 370 implement layer 1 functionality associated with
various signal processing functions. Layer 1, which includes a
physical (PHY) layer, may include error detection on the transport
channels, forward error correction (FEC) coding/decoding of the
transport channels, interleaving, rate matching, mapping onto
physical channels, modulation/demodulation of physical channels,
and MIMO antenna processing. The TX processor 316 handles mapping
to signal constellations based on various modulation schemes (e.g.,
binary phase-shift keying (BPSK), quadrature phase-shift keying
(QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude
modulation (M-QAM)). The coded and modulated symbols may then be
split into parallel streams. Each stream may then be mapped to an
OFDM subcarrier, multiplexed with a reference signal (e.g., pilot)
in the time and/or frequency domain, and then combined together
using an Inverse Fast Fourier Transform (IFFT) to produce a
physical channel carrying a time domain OFDM symbol stream. The
OFDM stream is spatially precoded to produce multiple spatial
streams. Channel estimates from a channel estimator 374 may be used
to determine the coding and modulation scheme, as well as for
spatial processing. The channel estimate may be derived from a
reference signal and/or channel condition feedback transmitted by
the UE 350. Each spatial stream may then be provided to a different
antenna 320 via a separate transmitter 318TX. Each transmitter
318TX may modulate an RF carrier with a respective spatial stream
for transmission.
[0059] At the UE 350, each receiver 354RX receives a signal through
the receiver's respective antenna 352. Each receiver 354RX recovers
information modulated onto an RF carrier and provides the
information to the receive (RX) processor 356. The TX processor 368
and the RX processor 356 implement layer 1 functionality associated
with various signal processing functions. The RX processor 356 may
perform spatial processing on the information to recover any
spatial streams destined for the UE 350. If multiple spatial
streams are destined for the UE 350, the multiple spatial streams
may be combined by the RX processor 356 into a single OFDM symbol
stream. The RX processor 356 then converts the OFDM symbol stream
from the time-domain to the frequency domain using a Fast Fourier
Transform (FFT). The frequency domain signal comprises a separate
OFDM symbol stream for each subcarrier of the OFDM signal. The
symbols on each subcarrier, and the reference signal, are recovered
and demodulated by determining the most likely signal constellation
points transmitted by the eNB 310. These soft decisions may be
based on channel estimates computed by the channel estimator 358.
The soft decisions are then decoded and deinterleaved to recover
the data and control signals that were originally transmitted by
the eNB 310 on the physical channel. The data and control signals
are then provided to the controller/processor 359, which implements
layer 3 and layer 2 functionality.
[0060] The controller/processor 359 can be associated with a memory
360 that stores program codes and data. The memory 360 may be
referred to as a computer-readable medium. In the UL, the
controller/processor 359 provides demultiplexing between transport
and logical channels, packet reassembly, deciphering, header
decompression, and control signal processing to recover IP packets
from the EPC 160. The controller/processor 359 is also responsible
for error detection using an ACK and/or NACK protocol to support
HARQ operations.
[0061] Similar to the functionality described in connection with
the DL transmission by the eNB 310, the controller/processor 359
provides RRC layer functionality associated with system information
(e.g., MIB, SIBs) acquisition, RRC connections, and measurement
reporting; PDCP layer functionality associated with header
compression/decompression, and security (ciphering, deciphering,
integrity protection, integrity verification); RLC layer
functionality associated with the transfer of upper layer PDUs,
error correction through ARQ, concatenation, segmentation, and
reassembly of RLC SDUs, re-segmentation of RLC data PDUs, and
reordering of RLC data PDUs; and MAC layer functionality associated
with mapping between logical channels and transport channels,
multiplexing of MAC SDUs onto TBs, demuliplexing of MAC SDUs from
TBs, scheduling information reporting, error correction through
HARQ, priority handling, and logical channel prioritization.
[0062] Channel estimates derived by a channel estimator 358 from a
reference signal or feedback transmitted by the eNB 310 may be used
by the TX processor 368 to select the appropriate coding and
modulation schemes, and to facilitate spatial processing. The
spatial streams generated by the TX processor 368 may be provided
to different antenna 352 via separate transmitters 354TX. Each
transmitter 354TX may modulate an RF carrier with a respective
spatial stream for transmission.
[0063] The UL transmission is processed at the eNB 310 in a manner
similar to that described in connection with the receiver function
at the UE 350. Each receiver 318RX receives a signal through the
receiver's respective antenna 320. Each receiver 318RX recovers
information modulated onto an RF carrier and provides the
information to a RX processor 370.
[0064] The controller/processor 375 can be associated with a memory
376 that stores program codes and data. The memory 376 may be
referred to as a computer-readable medium. In the UL, the
controller/processor 375 provides demultiplexing between transport
and logical channels, packet reassembly, deciphering, header
decompression, control signal processing to recover IP packets from
the UE 350. IP packets from the controller/processor 375 may be
provided to the EPC 160. The controller/processor 375 is also
responsible for error detection using an ACK and/or NACK protocol
to support HARQ operations.
[0065] FIG. 4 is an illustration of an example 400 of a wireless
communication 410 over an unlicensed radio frequency spectrum band,
in accordance with various aspects of the present disclosure. In
some examples, a listen before talk (LBT) radio frame 415 may have
a duration of ten milliseconds and include a number of downlink (D)
subframes 420, a number of uplink (U) subframes 425, and two types
of special subframes, an S subframe 430 and an S' subframe 435. The
S subframe 430 may provide a transition between downlink subframes
420 and uplink subframes 425, while the S' subframe 435 may provide
a transition between uplink subframes 425 and downlink subframes
420 and, in some examples, a transition between LBT radio
frames.
[0066] During the S' subframe 435, a downlink clear channel
assessment (CCA) procedure 445 may be performed by one or more base
stations, such as one or more of the base stations 102 described
with reference to FIG. 1, to reserve, for a period of time, a
channel of the contention-based shared radio frequency spectrum
band over which the wireless communication 410 occurs. Following a
successful downlink CCA procedure 445 by a base station, the base
station may transmit a preamble, such as a channel usage beacon
signal (CUBS) (e.g., a downlink CUBS (D-CUBS 450)) to provide an
indication to other base stations or apparatuses (e.g., UEs, WiFi
access points, etc.) that the base station has reserved the
channel. In some examples, a D-CUBS 450 may be transmitted using a
plurality of interleaved resource blocks. Transmitting a D-CUBS 450
in this manner may enable the D-CUBS 450 to occupy at least a
certain percentage of the available frequency bandwidth of the
contention-based shared radio frequency spectrum band and satisfy
one or more regulatory requirements (e.g., a requirement that
transmissions over an unlicensed radio frequency spectrum band
occupy at least 80% of the available frequency bandwidth). The
D-CUBS 450 may in some examples take a form similar to that of an
LTE/LTE-A cell-specific reference signal (CRS) or a channel state
information reference signal (CSI-RS). When the downlink CCA
procedure 445 fails, the D-CUBS 450 may not be transmitted.
[0067] The S' subframe 435 may include a plurality of OFDM symbol
periods (e.g., 14 OFDM symbol periods). A first portion of the S'
subframe 435 may be used by a number of UEs as a shortened uplink
(U) period 440. A second portion of the S' subframe 435 may be used
for the downlink CCA procedure 445. A third portion of the S'
subframe 435 may be used by one or more base stations that
successfully contend for access to the channel of the
contention-based shared radio frequency spectrum band to transmit
the D-CUBS 450.
[0068] During the S subframe 430, an uplink CCA procedure 465 may
be performed by one or more UEs, such as one or more of the UEs 104
described above with reference to FIG. 1, to reserve, for a period
of time, the channel over which the wireless communication 410
occurs. Following a successful uplink CCA procedure 465 by a UE,
the UE may transmit a preamble, such as an uplink CUBS (U-CUBS 470)
to provide an indication to other UEs or apparatuses (e.g., base
stations, WiFi access points, etc.) that the UE has reserved the
channel. In some examples, a U-CUBS 470 may be transmitted using a
plurality of interleaved resource blocks. Transmitting a U-CUBS 470
in this manner may enable the U-CUBS 470 to occupy at least a
certain percentage of the available frequency bandwidth of the
contention-based radio frequency spectrum band and satisfy one or
more regulatory requirements (e.g., the requirement that
transmissions over the contention-based radio frequency spectrum
band occupy at least 80% of the available frequency bandwidth). The
U-CUBS 470 may in some examples take a form similar to that of an
LTE/LTE-A CRS or CSI-RS. When the uplink CCA procedure 465 fails,
the U-CUBS 470 may not be transmitted.
[0069] The S subframe 430 may include a plurality of OFDM symbol
periods (e.g., 14 OFDM symbol periods). A first portion of the S
subframe 430 may be used by a number of base stations as a
shortened downlink (D) period 455. A second portion of the S
subframe 430 may be used as a guard period (GP) 460. A third
portion of the S subframe 430 may be used for the uplink CCA
procedure 465. A fourth portion of the S subframe 430 may be used
by one or more UEs that successfully contend for access to the
channel of the contention-based radio frequency spectrum band as an
uplink pilot time slot (UpPTS) or to transmit the U-CUBS 470.
[0070] In some examples, the downlink CCA procedure 445 or the
uplink CCA procedure 465 may include the performance of a single
CCA procedure. In other examples, the downlink CCA procedure 445 or
the uplink CCA procedure 465 may include the performance of an
extended CCA procedure. The extended CCA procedure may include a
random number of CCA procedures, and in some examples may include a
plurality of CCA procedures.
[0071] As indicated above, FIG. 4 is provided as an example. Other
examples are possible and may differ from what was described in
connection with FIG. 4.
[0072] In LTE networks with a licensed carrier and one or more
unlicensed carriers, DL grants and UL grants may generally be
scheduled using a self-scheduling mode and/or a cross-carrier
scheduling mode. In the self-scheduling mode, the UE utilizes the
same carrier to receive a grant for data communication and to
schedule a resource for data communication based on the grant. In
particular, the UE is configured to receive a DL grant and to
receive DL data based on the DL grant on the same carrier, and the
UE is configured to receive a UL grant and to transmit UL data
based on the UL grant on the same carrier. Thus, in the
self-scheduling mode, reception of a DL grant and an UL grant, and
communication of DL data and UL data is performed on the same
carrier. In the cross-carrier scheduling mode, the UE may utilize
one carrier to receive a grant and utilize another carrier to
schedule a resource for data communication based on the grant. In
particular, the UE may be configured to receive a DL grant and a UL
grant on one carrier (e.g., a first carrier), and may be configured
to receive DL data on a different carrier (e.g., a second carrier)
and to transmit UL data on a different carrier (e.g., the second
carrier or a third carrier). Thus, in the cross-carrier scheduling
mode, reception of a DL grant and communication of DL data are
performed on different carriers, and reception of a UL grant and
communication of UL data are performed on different carriers.
[0073] FIG. 5A illustrates an example diagram 500 of a
self-scheduling mode. On the primary component carrier (PCC) of the
diagram 500, the UE receives a grant (e.g., a UL grant or a DL
grant) in the control region 512 of the PCC and communicates data
(e.g., UL data based on the UL grant or DL data based on the DL
grant) in the data region 514 of the PCC, as indicated by the arrow
516. On the secondary component carrier (SCC) of the diagram 500,
the UE receives a grant (e.g., a UL grant or a DL grant) in the
control region 522 of the SCC and communicates data (e.g., UL data
based on the UL grant or DL data based on the DL grant) in the data
region 524 of the SCC, as indicated by the arrow 526.
[0074] FIG. 5B illustrates an example diagram 550 of a
cross-carrier scheduling mode. On the PCC of the diagram 550, the
UE receives a grant (e.g., a UL grant or a DL grant) in the control
region 562 of the PCC. After receiving the grant in the control
region 562 of PCC, the UE may communicate data (e.g., UL data based
on the UL grant or DL data based on the DL grant) in the data
region 574 of the SCC, thereby performing cross-carrier scheduling
of the data communication between the PCC and SCC as indicated by
the arrow 576. The SCC may include a control region 572 or may not
include any control region. Optionally, the UE may be additionally
configured to communicate data in the data region 564 of the PCC
based on the received grant.
[0075] As discussed supra, CCs may be aggregated together via
carrier aggregation and may be configured with either an FDD
configuration or with a TDD configuration. For a cross-carrier
scheduling mode on an SCC using an FDD PCC, if a DL grant is
received in subframe n of the PCC, the DL data is received in
subframe n of the SCC based on the DL grant. In addition, for a
cross-carrier scheduling mode on an SCC using a FDD PCC, if a UL
grant is received in subframe n-4 of the PCC, the UL data is
received in subframe n of the SCC based on the UL grant. For a
cross-carrier scheduling mode on an SCC using TDD PCC, a DL grant
for receiving DL data on subframe n of the SCC may be scheduled on
the PCC when a DL subframe is present in the PCC. For a
cross-carrier scheduling mode on an SCC using TDD PCC, the UL grant
for transmitting UL data on subframe n of the SCC may be received
in subframe n-4, n-5, n-6, etc., depending on the TDD configuration
of the PCC.
[0076] It is noted that channel availability may not be certain
when utilizing an unlicensed carrier. In particular, scheduling
grants in advance may be difficult because of difficultly when
determining available channels. At least for these reasons,
scheduling UL and/or DL grants in advance may not be feasible when
utilizing an unlicensed carrier or may result in wastage of RBs
and/or underutilization of RBs even when the UL and/or DL grants
are scheduled in advance. Therefore, a new scheduling scheme to
improve utilization of an unlicensed carrier may be desired.
[0077] FIG. 6A and FIG. 6B are example diagrams illustrating uses
of a primary serving cell served by a PCC and a secondary serving
cell served by an SCC for uplink communication. The PCC may be a
component carrier operating in a licensed spectrum, and the SCC may
be a carrier operating on unlicensed spectrum. However, in other
implementations either may be licensed or unlicensed.
[0078] FIG. 6A is an example diagram 600 illustrating a mismatch
that may result from DL cross-carrier scheduling, using the primary
serving cell (the PCell) to communicate DL grants for a secondary
serving cell (the SCell). The PCell is served by the PCC, and the
SCell is served by the SCC. The Example diagram 600 illustrates a
situation where the TDD configuration of the primary serving cell
prevents the eNB from scheduling a DL grant for the SCC of the
SCell. Specifically, in this example, since timing of UL subframes
(e.g., UL subframes 602, 604, and 606) in the PCell overlaps with
timing of DL subframes (e.g., DL subframes 612, 614, and 616) in
the SCell, the eNB cannot provide DL grants in UL subframes 602,
604, and 606 for DL communication on DL subframes 612, 614, and
616, respectively. Since the UE cannot receive a DL grant on the UL
subframes (602, 604, and 606) in the PCell, the UE cannot perform
data communication on DL subframes 612, 614, and 616 and thus
misses a data communication opportunity.
[0079] FIG. 6B is an example diagram 650 illustrating both UL
cross-carrier scheduling 666 and UL self-scheduling 652.
[0080] When using self-scheduling (e.g., UL self-scheduling 652),
channel availability may be determined by performing a two level
checking procedure. In a first level of the checking procedure, the
eNB checks for an available channel for transmission of a grant,
and transmits the grant using the available channel. In a second
level of the checking procedure, after the UE receives the grant,
the UE checks for an available channel for data communication based
on the grant. When using UL self-scheduling 652, if none of the
subframes 654, 656, 658, 660, and 662 are available for the UE to
receive a UL grant from the eNB, then the UE will be unable to
perform UL communication on the UL subframe 664 due to lack of a UL
grant. Furthermore, since the UE may need to receive the UL grant
at least 4 subframes before UL communication, lack of an available
channel in subframes 654 and 656 may cause the UE to miss a UL
transmission opportunity in the UL subframe 664.
[0081] An alternative to UL self-scheduling 652 is to use UL
cross-carrier scheduling 666. In UL cross-carrier scheduling 666,
the UE receives an UL grant from the PCell, and transmits UL data
to the SCell based on the UL grant. When using cross-carrier
scheduling 666, the UE receives an UL grant in a subframe 668 of
the PCell. Because the PCC of the PCell is a licensed carrier, the
eNB does not need to check for a channel that is available for
transmission of the UL grant. Therefore, in the cross-carrier
scheduling, the first level of the checking procedure for an
available channel may not be necessary. After receiving the UL
grant in the subframe 668 from the PCell, the UE may transmit UL
data in the UL subframe 664 to the SCell.
[0082] According to the disclosure, the UE and eNB may use a
combination of self-scheduling and cross-carrier scheduling. DL
cross-carrier scheduling may experience the following problem when
a licensed carrier and unlicensed carrier are used. When the eNB
(e.g., during cross-carrier scheduling) transmits a DL grant on a
licensed carrier (e.g., the PCC), the eNB does not know whether a
channel is available on an unlicensed carrier (e.g., the SCC) for
DL communication on the SCC. If no channel is available for DL
communication on the SCC when the DL grant is received by the UE,
the UE may not be able to receive the DL communication. Thus, the
eNB keeps scheduling a DL grant and the UE repeatedly attempts to
receive DL communication until successful DL communication is
performed on an available channel, which may not be desirable for
the UE. Hence, for the DL communication, self-scheduling may be
more advantageous than cross-carrier scheduling. On the other hand,
for UL communication, UL cross-carrier scheduling may not
experience the same problem as the DL cross-carrier scheduling. In
particular, the eNB sends a UL grant some time before receiving a
UL communication (e.g., 4 msec before receiving the UL
communication), and thus the eNB may have sufficient time to
allocate an available channel for the UL communication. For
example, for the UL cross-carrier scheduling, because the eNB has
sufficient time to allocate an available channel for the UL
communication after sending the UL grant, the UE may not need to
repeatedly attempt to transmit UL communication until successful UL
communication on an available channel. The UE receives the UL grant
on the licensed carrier and performs the UL communication on an
unlicensed carrier. Thus, for example, the eNB may not need to
check for channel availability when sending the UL grant on the
licensed carrier.
[0083] Therefore, according to an aspect of the disclosure, a
self-scheduling mode may be utilized for DL grants and a
cross-carrier scheduling mode may be utilized for UL grants. In
particular, according to the aspect, for the DL communication
utilizing the self-scheduling mode, the UE may receive a DL grant
and subsequently receive DL data on the same carrier. For UL
communication utilizing the cross-carrier scheduling mode, the UE
may receive a UL grant on one carrier and may transmit UL data to
the eNB on another carrier. For example, the UE may be configured
to receive, on a secondary carrier, a DL grant for the secondary
carrier, and to receive DL data on the secondary carrier based on
the DL grant, according to the self-scheduling mode. Further,
according to the cross-carrier scheduling mode, the UE may be
configured to receive, on a primary carrier, a UL grant for the
secondary carrier and transmit UL data on the secondary carrier
based on the UL grant. For example, the primary carrier may be a
licensed carrier (e.g., a PCC) and the secondary carrier may be an
unlicensed carrier (e.g., an SCC).
[0084] FIG. 7 is an example diagram 700 illustrating
self-scheduling and cross-carrier scheduling according to an aspect
of the disclosure. A PCC in FIG. 7 has a control region 712 and a
data region 714, and an SCC in FIG. 7 has a control region 722 and
a data region 724. A UE (e.g., UE 752) may utilize the
cross-carrier scheduling mode for the UL communication. In
particular, the UE 752 may receive at 762, from the eNB 754, a UL
grant in the control region 712 of the PCC, where the UL grant is
for UL communication on the SCC. After receiving the UL grant on
the PCC, the UE 752 may transmit at 764 to the eNB 754, based on
the UL grant, UL data in the data region 724 of the SCC, as
indicated by the arrow 726. The UE 752 may utilize the
self-scheduling mode for the DL communication. In particular, the
UE 752 may receive at 772, from the eNB 754, a DL grant in the
control region 722 of the SCC, where the DL grant is for DL
communication on the SCC. After receiving the DL grant on the SCC,
the UE 752 may receive at 774, from the eNB 754, DL data in the
data region 724 of the SCC based on the DL grant, as indicated by
the arrow 728.
[0085] Aspects of the disclosure may provide several advantages as
follows. Firstly, when the eNB self-schedules a DL communication on
a secondary carrier that is an unlicensed carrier, the UE will be
able to receive the DL grant on the secondary carrier as long as
the eNB has access to a channel for communicating the DL grant to
the UE. If the eNB does not have access to a channel, the eNB may
not schedule the DL grant. Because the eNB may determine to
schedule the DL grant based on whether the eNB already has access
to a channel, the eNB does not attempt to utilize the secondary
carrier for the DL grant unless the eNB determines whether the eNB
has access to a channel for DL communication, which reduces
instances of invalid grants being used at the UE. Further,
utilizing the secondary carrier to receive the DL grant may save
resources on the primary carrier that is a licensed carrier and may
reduce grant overload on the primary carrier. Secondly, because the
eNB transmits the UL grant on the primary carrier that is a
licensed carrier, the eNB may not need to check for channel
availability. In other words, contrary to the transmission of the
grant on an unlicensed carrier, the eNB, when scheduling a UL grant
for transmission on a licensed carrier, does not need to check for
channel availability. Thus, transmission of the UL data does not
depend on the channel availability for receiving the UL grant.
[0086] In an aspect of the disclosure, UE complexity may be reduced
using an approach by the disclosure. The UE complexity may increase
as a number of UE searches for downlink control information (DCI)
format sizes (format sizes of DCI messages) increases. Thus,
according to the aspect, the UE complexity may be reduced by
reducing the number of UE searches. If both a DL grant and a UL
grant are communicated on the same carrier, the UE may search for a
format size of a DCI message to obtain the UL grant and/or the DL
grant on the same carrier. If a DL grant is communicated on a first
carrier and a UL grant is communicated on a second carrier
different from the first carrier, the UE may search for a format
size of a DCI message for the DL grant on the first carrier and
additionally search for a format size of a DCI message for the UL
grant on the second carrier. For example, when scheduling on the
PCC, a DL grant and a UL grant may correspond to the same format
size of a DCI message, and thus the UE may find the DL grant and
the UL grant by searching for the same format size of the DCI
message. If the DL grant is communicated on the SCC and the UL
grant is communicated on the PCC, then the UE searches for a format
size of a DCI message for the DL grant on the SCC and additionally
searches for a format size of a DCI message for the UL grant on the
PCC, which may increase UE complexity. In such a case, the UE may
search on the SCC for a format size of a DCI message that is
specific to a transmission mode (TM) and also search for a fallback
mode format size of a DCI message (e.g., a size of Format 1A grant
of Format 0/1A) when searching for a DL grant. It is noted that
Format 1A of the DCI message may be used as a fallback mode for DL
scheduling. For example, if a UE is configured to operate in TM 4,
the UE may search for two format sizes on the SCC (e.g., when
searching for a DL grant). One format size to be searched may be a
DCI format size corresponding to TM 4, which is DCI Format 2. The
other format size to be searched may be a DCI format size
corresponding to DCI Format 1A. The UE may also search on the PCC
for a format size of a DCI format (e.g., Format 0 grant of Format
0/1A) when searching for a UL grant. It is noted that Format 0 of
the DCI message may be used for UL scheduling. In one aspect, to
reduce the UE complexity, the following two approaches may be
utilized.
[0087] According to a first approach of the aspect, in order to
monitor for the UL grant and/or the DL grant, the UE may be
configured to search on the SCC for a DCI format size that is
specific to a TM, without searching for a fallback mode format size
of a DCI message. For example, according to the first approach of
the aspect, if a UE is configured to operate with TM 4, the UE may
search for a DCI format size corresponding to TM 4, which is DCI
Format 2, and may not search for a size corresponding to DCI Format
1A associated with a fallback mode. In the first approach of the
aspect, the UE may assume that there is no fall back mode on the
SCC, and perform a TM-specific size search. Because the first
approach reduces the number of searches performed by the UE, by
limiting searching to the DCI format size specific to a TM without
searching for fallback mode format size of a DCI message, the first
approach may reduce the UE complexity.
[0088] According to a second approach of the aspect, the eNB may
provide the UE with blind decode information on a number of blind
decodes (e.g., a maximum number of blind decodes) to perform per
subframe, to detect a UL grant and/or a DL grant. The eNB may
provide the UE with such blind decode information semi-statically.
In particular, according to the blind decode information, the UE
may decode all candidates for a UL grant and/or a DL grant in some
subframes, and may decode a subset of candidates for a UL grant
and/or a DL grant in other subframes, based on the number of blind
decodes specified in the blind decode information. For example, the
UE may decode for both a DL grant and a UL grant in some subframes
if the blind decode information provides a maximum number of blind
decodes, and may decode either a DL grant or a UL grant in the
subframes if the blind decode information provides less number of
blind decodes. In the second approach, UE complexity may be reduced
because not all candidates are decoded for every subframe, unlike a
configuration where all candidates are decoded for every
subframe.
[0089] In another aspect of the disclosure, a cross-carrier
indicator may be communicated to a UE on one carrier to indicate
that a grant will be sent on another carrier. For example, in
self-scheduling for DL communication, the eNB may send a
cross-carrier indicator to the UE on the PCC to indicate that a DL
grant will be sent on the SCC. It is noted that transmitting a DL
grant on the PCC for the DL data communication on the SCC may incur
more overhead on the PCC. In this aspect of the disclosure, because
a eNB does not send the DL grant on the PCC, the amount of overhead
on the PCC and/or a number of blind decodes performed by the UE may
be reduced. Because presence or absence of a DL grant on the SCC is
indicated in the cross-carrier indicator received on the PCC, the
UE may monitor for the DL grant on the SCC based on the
cross-carrier indicator. Utilizing the cross-carrier indicator
instead of transmitting a DL grant on the PCC may reduce UE
complexity (e.g., by reducing the number of blind decodes by the
UE). Further, utilizing the cross-carrier indicator may reduce
adverse impact of signal interference causing the UE to fail to
utilize a DL grant for DL communication. For example, if the UE
attempts to receive a DL grant on a SCC for DL data communication
on the SCC, the UE may not be able to decode the DL grant due to
high signal interference. The UE may not report a message
indicating acknowledge/negative-acknowledge (ACK/NACK message) of a
DL grant when the UE fails to decode the DL grant and thus does not
receive the DL grant. This in turn may cause the UE and the eNB to
be out of synchronization. Because a licensed spectrum is more
reliable than an unlicensed spectrum, the UE may successfully
receive the cross-carrier indicator on the licensed spectrum, e.g.,
the PCC, to indicate the presence of the DL grant on the SCC. The
UE may report to the eNB an ACK/NACK message for the DL grant on
the SCC, based on the cross-carrier indicator received on the PCC,
even if the UE does not receive the DL grant on the SCC due to high
signal interference. This may reduce the chances of the UE and eNB
getting out of synchronization.
[0090] Several approaches may be utilized to indicate the
cross-carrier indication to the UE. According to one approach, the
eNB may include the cross-carrier indicator in a new DCI message
with a new format and transmit the new DCI message with the new
format on the PCC in a common search space. The cross-carrier
indicator may be protected with a new RNTI that is known to a group
of UEs. The size of the new DCI message with the new DCI format may
be the same as the size of an existing DCI message. The eNB may
indicate to each UE via an RRC configuration that certain bits in
the new DCI message on the PCC may be monitored for the
cross-carrier indicator to determine if a DL grant is
communicated.
[0091] According to another approach, instead of a group indication
of a grant, the eNB may indicate separately to each UE whether
there is a grant or not. In particular, the eNB may provide a
separate indication to each UE by sending a DCI message including a
cross-carrier indicator in a corresponding UE-specific search space
of each UE, instead of sending the DCI message in the common search
space.
[0092] In another aspect of the disclosure, the eNB may configure
the scheduling mode as a function of a TDD subframe configuration.
Table 1 illustrates example TDD DL/UL subframe configurations that
may be utilized for the PCell and/or the SCell.
TABLE-US-00001 TABLE 1 LTE TDD DL/UL Subframe Configurations
Downlink- Uplink- to-uplink downlink Switch- config- point Subframe
number uration periodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S
U U U 1 5 ms D S U U D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms
D S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms D S U D D D
D D D D 6 5 ms D S U U U D S U U D
[0093] In particular, scheduling for UL communication may depend on
whether the TDD subframe configuration used by the SCell is a DL
heavy configuration or a UL heavy configuration. A subframe
configuration with more DL subframes than other types of subframes
may be considered a DL heavy TDD configuration. A subframe
configuration with more UL subframes than other types of subframes
may be considered a UL heavy TDD configuration. For example,
Subframe Configuration #5 may be considered a DL heavy TDD
configuration because there are eight DL subframes out of ten
subframes. For example, Subframe Configuration #0 may be considered
a UL heavy TDD configuration because there are six UL subframes out
of ten subframes. For UL communication, if the SCell uses a DL
heavy configuration, the SCell may schedule UL data communication
on an unlicensed carrier using a UL grant on the unlicensed carrier
(e.g., self-scheduling for UL). It is noted that, for DL
communication, self-scheduling is utilized regardless of whether
the SCell uses a DL heavy configuration or a UL heavy
configuration. Thus, according to this aspect of the disclosure,
utilizing the DL heavy TDD configuration by the SCell results in
self-scheduling for both UL and DL communications. On the contrary,
for UL communication, if the SCell uses a UL heavy TDD
configuration, the PCell may utilize cross-carrier scheduling for
UL communication. For DL communication, as discussed above,
self-scheduling is utilized regardless of whether the SCell uses a
DL heavy configuration or a UL heavy configuration. Thus, utilizing
the UL heavy TDD configuration by the SCell results in
cross-carrier scheduling for UL communication and self-scheduling
for DL communication.
[0094] In an aspect, the eNB may configure the scheduling mode for
each of the carriers independently, where the carriers may include
a licensed carrier (e.g., the PCC) and one or more unlicensed
carriers (e.g., one or more SCCs). The eNB may configure the
scheduling mode independently for each of the carriers based on
signal interference and channel occupancy observed on each carrier.
For example, the eNB may first perform a CCA procedure to clear a
channel for transmitting information (e.g., a grant) to the UE. A
channel may be cleared if an energy observed in the channel is
lower than an energy threshold. For example, if the channel is
occupied by another device or experiences strong interference, the
channel may observe high energy above the energy threshold and thus
the eNB may not be able to clear the channel. The signal
interference and channel occupancy on a channel may be reflected by
whether a channel can be cleared for communication. It is noted
that some eNBs (e.g., eNBs with multi-antenna receivers) may be
able to receive UL data from the UE even if no channel is cleared.
In such a case, the eNB may still send the UL grant on a licensed
carrier (e.g., PCC) and receive UL data on an unlicensed carrier
(e.g., SCC), and thus may not be affected by interference or
channel occupancy.
[0095] In another aspect of the disclosure, a UL grant transmitted
on the PCC may be mapped to a group of unlicensed carriers for UL
data transmission based on the UL grant. When the UE receives a UL
grant, the UE may be configured to determine whether the UL grant
is mapped to a group of unlicensed carriers. The UE may transmit
the UL data on any available (e.g., cleared) channel among the
group of unlicensed carriers mapped to the UL grant. The UE may
select a carrier to transmit the UL data from among the group of
unlicensed carriers based on channel availability and/or priority
of carriers. The channel availability may depend on whether a
channel is cleared or not (e.g., CCA procedure), as discussed
supra. For example, if three channels corresponding to three
unlicensed carriers are cleared, the UE may select a channel
associated with an unlicensed carrier of the highest priority, and
transmit the UL data on the unlicensed carrier corresponding to the
selected channel. The eNB may blind detect the unlicensed carrier
that the UE uses to transmit the UL data.
[0096] In another aspect of the disclosure, a scalable enhanced
PDCCH (EPDCCH) may be used. An EPDCCH may be used for resource
allocation of control channel information. In particular, the eNB
may assign resource blocks (RBs) to the EPDCCH. When the UE
receives the EPDCCH from the eNB, the UE may determine, based on
the EPDCCH, a certain set of RBs to monitor for subframes that
carry UL grants. The number of RBs to monitor may be fixed
semi-statically by the eNB. The number of grants that a subframe
carries may vary depending on the subframe. Some DL subframes may
carry more grants than other subframes if those grants are used to
schedule UL subframes for multiple carriers in an unlicensed
spectrum. For example, if a subframe has a lot of UL grants, more
search space may be needed. For example, when using a TDD subframe
configuration with two or three DL subframes (thus eight or seven
UL subframes), each DL subframe may carry multiple UL grants for
multiple subframes, which may benefit from a larger search space
and more resources for monitoring UL grants. Therefore, according
to an aspect of the disclosure, a scalable EPDCCH design is used
such that an eNB may adjust the number of RBs/candidates to be
monitored by the UE for a predetermined set of subframes which
carry UL grants. The number of RBs and candidates (e.g., candidates
for grants and/or a PDCCH) to monitor may be a function of the TDD
configuration and/or the number of active unlicensed carriers.
Depending on the TDD subframe configuration, the search space for
the UL grant may be increased or reduced. For example, if the TDD
configuration is a UL heavy configuration having more UL subframes
than other subframes, the eNB may assign more resource blocks to
the EPDCCH, thereby increasing a search space for UL grants. On the
contrary, if the TDD configuration is a DL heavy configuration
having more DL sub frames than other subframes, the eNB may assign
less resource blocks to the EPDCCH, thereby reducing a search space
for UL grants. In addition, the eNB may configure a number of
candidates or aggregation levels to monitor in a PDCCH, and may
further configure at least one of a number of sets of EPDCCHs, a
number of resource blocks (RBs) for each set of EPDCCHs, a type of
EPDCCH, or a number of candidates or aggregation levels for EPDCCH
monitoring.
[0097] FIG. 8 is a flow chart 800 of a method of wireless
communication. The method may be performed by a UE (e.g., the UE
104, the UE 752, the apparatus 1102/1102'). At block 801, one or
more additional methods discussed infra may be performed. Blocks
with dotted lines may include optional features or steps.
[0098] In one aspect, at block 802, the UE may receive, on the
primary carrier, a DL grant indicator, where the DL grant indicator
indicates whether the UE should monitor at least one of the primary
carrier or the secondary carrier for the DL grant. In an aspect,
the DL grant indicator is received in a DCI message on the primary
carrier in a common search space and is protected with an RNTI that
is known to a group of UEs. In such an aspect, the UE monitors for
the DL grant indicator in the DCI message on the primary carrier
based on an RRC configuration. In an aspect, the DL grant indicator
is received on the primary carrier in a search space that is
specific to a user equipment.
[0099] For example, as discussed supra, in self-scheduling for DL
communication, the eNB may send a cross-carrier indicator to the UE
on the PCC to indicate that a DL grant will be sent on the SCC. For
example, as discussed supra, because presence or absence of a DL
grant on the SCC is indicated in the cross-carrier indicator
received on the PCC, the UE may monitor for the DL grant on the SCC
based on the cross-carrier indicator. For example, as discussed
supra, the eNB may include the cross-carrier indicator in a new DCI
message with a new format and transmit the new DCI message with the
new format on the PCC in the common search space, and the
cross-carrier indicator may be protected with a new RNTI that is
known to a group of UEs. For example, as discussed supra, the eNB
may provide a separate indication to a UE by sending a DCI message
including a cross-carrier indicator in a UE-specific search space,
instead of sending the DCI message in the common search space.
[0100] At block 804, the UE receives a DL grant for a secondary
carrier and a UL grant for the secondary carrier, where the DL
grant is received on the secondary carrier and the UL grant is
received on a primary carrier. For example, as discussed supra, the
UE may be configured to receive, on a secondary carrier, a DL grant
for the secondary carrier, and to receive, on a primary carrier, a
UL grant for the secondary carrier. For example, referring back to
FIG. 7, the UE 752 may receive, at 762, a UL grant in the control
region 712 of the PCC, where the UL grant is for UL communication
on the SCC, and may receive, at 772, a DL grant in the control
region 722 of the SCC, where the DL grant is for DL communication
on the SCC.
[0101] At block 806, the UE may receive DL data on the secondary
carrier after receiving the DL grant on the secondary carrier. For
example, as discussed supra, the UE may be configured to receive DL
data on the secondary carrier based on the DL grant, according to
the self-scheduling mode. For example, referring back to FIG. 7,
after receiving the DL grant on the SCC, the UE 752 may receive, at
774, DL data in the data region 724 of the SCC based on the DL
grant, as indicated by the arrow 728.
[0102] At block 808, the UE may transmit UL data on the secondary
carrier after receiving the UL grant on the primary carrier. For
example, as discussed supra, according to the cross-carrier
scheduling mode, the UE may be configured to receive, on a primary
carrier, a UL grant for the secondary carrier and transmit UL data
on the secondary carrier based on the UL grant. For example,
referring back to FIG. 7, after receiving the UL grant on the PCC,
the UE 752 may transmit, at 764, based on the UL grant, UL data in
the data region 724 of the SCC, as indicated by the arrow 726.
[0103] In an aspect, the primary carrier is a licensed carrier and
the secondary carrier is an unlicensed carrier. In an aspect, the
DL grant and the UL grant are received from a base station using a
configuration where DL grants are received by the UE on the
secondary carrier and UL grants are received by the UE on the
primary carrier. In an aspect, the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are scheduled by self-scheduling on the secondary carrier and UL
grants are scheduled by cross-carrier scheduling on the primary
carrier. For example, as discussed supra, the primary carrier may
be a licensed carrier (e.g., a PCC) and the secondary carrier may
be an unlicensed carrier (e.g., an SCC).
[0104] FIG. 9A is a flow chart 900 of a method of wireless
communication expanding from the flow chart 800 of FIG. 8,
according to an aspect of the disclosure. The method may be
performed by a UE (e.g., the UE 104, the UE 752, the apparatus
1102/1102'). The flow chart 900 expands from block 801 of FIG. 8.
For example, the method in the flow chart 900 may be performed to
monitor for a DL grant and/or a UL grant, such that the UE may
receive the DL grant and the UL grant at block 804 of FIG. 8. In an
aspect, the UE may continue at block 802 or block 804 of FIG. 8
after performing the features of the flow chart 900.
[0105] At block 902, the UE may receive information about at least
one of a set of DCI formats or DCI format sizes of respective DCI
messages to monitor on each subframe on each carrier. For example,
as discussed supra, if a DL grant is communicated on a first
carrier and a UL grant is communicated on a second carrier
different from the first carrier, the UE may search for a format
size of a DCI message for the DL grant on the first carrier and
additionally search for a format size of a DCI message for the UL
grant on the second carrier. For example, in one aspect, the UE may
receive the information about the at least one of a set of DCI
formats or DCI format sizes of respective DCI messages by analyzing
on the DCI messages received by the UE.
[0106] At block 904, the UE monitors for at least one of the UL
grant or the DL grant based on the information. In an aspect, each
of the DCI format sizes of the respective DCI messages is specific
to a transmission mode. For example, as discussed supra, the UE may
be configured to search on the SCC for a DCI format size that is
specific to a TM, in order to monitor for the UL grant and/or the
DL grant, without searching for a fallback mode format size of a
DCI message. For example, as discussed supra, the UE may assume
that there is no fall back mode on the SCC, and perform a
TM-specific size search.
[0107] FIG. 9B is a flow chart 950 of a method of wireless
communication expanding from the flow chart 800 of FIG. 8,
according to an aspect of the disclosure. The method may be
performed by a UE (e.g., the UE 104, the UE 752, the apparatus
1102/1102'). The flow chart 950 expands from block 801 of FIG. 8.
For example, the method in the flow chart 950 may be performed to
detect a DL grant and/or a UL grant, such that the UE may receive
the DL grant and the UL grant at block 804 of FIG. 8. In an aspect,
the UE may continue at block 802 or block 804 of FIG. 8 after
performing the operations of the flow chart 950.
[0108] At block 952, the UE may receive information on a number of
blind decodes to perform per subframe. For example, as discussed
supra, the UE may receive from the eNB blind decode information on
a number of blind decodes (e.g., a maximum number of blind decodes)
to perform per subframe, to detect a UL grant and/or a DL grant.
For example, as discussed supra, the UE may receive from the eNB
such blind decode information semi-statically.
[0109] At block 954, the UE may blind decode based on the number of
blind decodes to detect at least one of the DL grant or the UL
grant. For example, as discussed supra, according to the blind
decode information, the UE may decode all candidates in some
subframes, and may decode a subset of candidates, based on the
number of blind decodes specified in the blind decode information.
For example, as discussed supra, the UE may decode both a DL grant
and a UL grant for some subframes if the blind decode information
provides a maximum number of blind decodes, and may decode either a
DL grant or a UL grant if the blind decode information provides
less number of blind decodes.
[0110] FIG. 10A is a flow chart 1000 of a method of wireless
communication expanding from the flow chart 800 of FIG. 8,
according to an aspect of the disclosure. The method may be
performed by a UE (e.g., the UE 104, the UE 752, the apparatus
1102/1102'). The flow chart 1000 expands from block 801 of FIG. 8.
For example, the method in the flow chart 1000 may be performed to
select a carrier to transmit UL data, such that the UE may transmit
the UL data at block 808 of FIG. 8. In an aspect, the UE may
continue at block 802 or block 804 of FIG. 8 after performing the
features of the flow chart 1000.
[0111] At block 1002, where the UL grant received on the primary
carrier corresponds to a plurality of unlicensed carriers, the UE
selects a carrier from among the plurality of unlicensed carriers
as the secondary carrier to transmit the UL data. In an aspect, the
UE selects the carrier from among the plurality of unlicensed
carriers by determining channel availability of channels associated
with the plurality of unlicensed carriers, where a channel is
available when an energy of the channel is lower than an energy
threshold, and selecting the carrier associated with the channel
for transmission of the UL data based on at least one of the
channel availability or a carrier priority.
[0112] For example, as discussed supra, when the UE receives a UL
grant, the UE may be configured to determine whether the UL grant
is mapped to a group of unlicensed carriers. For example, as
discussed supra, the UE may select a carrier to transmit the UL
data from among the group of unlicensed carriers based on channel
availability and/or priority of the carriers, where the channel
availability may depend on whether a channel is cleared or not.
[0113] FIG. 10B is a flow chart 1050 of a method of wireless
communication expanding from the flow chart 800 of FIG. 8,
according to an aspect of the disclosure. The method may be
performed by a UE (e.g., the UE 104, the UE 752, the apparatus
1102/1102'). The flow chart 1050 expands from block 801 of FIG. 8.
For example, the method in the flow chart 1050 may be performed to
monitor for a UL grant, such that the UE may receive the UL grant
at block 804 of FIG. 8. In an aspect, the UE may continue at block
802 or block 804 of FIG. 8 after performing the features of the
flow chart 1050.
[0114] At block 1052, the UE may receive configuration information
from a serving base station adjusting a number of resource blocks
to monitor for receiving the UL grant. For example, as discussed
supra, a scalable EPDCCH design may be used such that the serving
base station (e.g., an eNB) may adjust the number of RBs/candidates
to be monitored by the UE for a defined set of subframes which may
carry UL grants. For example, as discussed supra, when the UE
receives the EPDCCH from the eNB, the UE determines, based on the
EPDCCH, a certain set of RBs to monitor for subframes that may
carry UL grants.
[0115] At block 1054, the UE monitors for the UL grant based on the
received configuration information adjusting the number of resource
blocks to monitor for receiving the UL grant. For example, as
discussed supra, depending on the TDD subframe configuration, the
search space for the UL grant may be increased or reduced. For
example, as discussed supra, if the TDD configuration has more UL
subframes than other subframes, more resource blocks may be
assigned to the EPDCCH, thereby increasing a search space for UL
grants. For example, as discussed supra, if the TDD configuration
has more DL subframes than other subframes, less resource blocks
may be assigned to the EPDCCH, thereby reducing a search space for
UL grants.
[0116] FIG. 11 is a conceptual data flow diagram 1100 illustrating
the data flow between different means/components in an exemplary
apparatus 1102. The apparatus may be a UE. The apparatus includes a
reception component 1104, a transmission component 1106, a grant
management component 1108, a data communication component 1110, a
grant indicator component 1112, a carrier selection component 1114,
and a resource management component 1116.
[0117] The grant management component 1108 receives from the eNB
1150 at 1152 and 1154, via the reception component 1104, a DL grant
for a secondary carrier and a UL grant for the secondary carrier,
where the DL grant is received on the secondary carrier and the UL
grant is received on a primary carrier. The data communication
component 1110 receives from the eNB 1150 at 1152 and 1156, via the
reception component 1104, DL data on the secondary carrier after
receiving the DL grant on the secondary carrier via 1158. The data
communication component 1110 transmits to the eNB 1150 at 1160 and
1162, via the transmission component 1106, UL data on the secondary
carrier after receiving the UL grant on the primary carrier via
1158. In an aspect, the primary carrier is a licensed carrier and
the secondary carrier is an unlicensed carrier. In an aspect, the
DL grant and the UL grant are received from a base station using a
configuration where DL grants are received by the UE on the
secondary carrier and UL grants are received by the UE on the
primary carrier. In an aspect, the DL grant and the UL grant are
received from a base station using a configuration where DL grants
are scheduled by self-scheduling on the secondary carrier and UL
grants are scheduled by cross-carrier scheduling on the primary
carrier.
[0118] The grant management component 1108 receives at 1152 and
1154 via the reception component 1104 information about at least
one of a set of DCI formats or DCI format sizes of respective DCI
messages to monitor on each subframe on each carrier. The grant
management component 1108 monitors via 1152 and 1154 for at least
one of the UL grant or the DL grant based on the information. In an
aspect, each of the DCI format sizes of the respective DCI messages
is specific to a transmission mode.
[0119] The grant management component 1108 receives at 1154 via the
reception component 1104 information at 1152 (from the eNB 1150) on
a number of blind decodes to perform per subframe. The grant
management component 1108 blind decodes based on the number of
blind decodes to detect at least one of the DL grant or the UL
grant.
[0120] The grant indicator component 1112 may receive at 1164, via
the reception component 1104 at 1152, on the primary carrier, a DL
grant indicator, where the DL grant indicator indicates whether the
UE should monitor (e.g., at 1166 via the grant management component
1108) at least one of the primary carrier or the secondary carrier
for the DL grant. In an aspect, the DL grant indicator is received
in a DCI message on the primary carrier in a common search space
and is protected with an RNTI that is known to a group of UEs. In
such an aspect, the grant indicator component 1112 monitors via
1152 and 1164 for the DL grant indicator in the DCI message on the
primary carrier based on an RRC configuration. In an aspect, the DL
grant indicator is received on the primary carrier in a search
space that is specific to a user equipment.
[0121] Where the UL grant received on the primary carrier
corresponds to a plurality of unlicensed carriers, the carrier
selection component 1114 selects a carrier from among the plurality
of unlicensed carriers as the secondary carrier to transmit the UL
data, where information about unlicensed carriers may be provided
by the reception component 1104 at 1168. In an aspect, the carrier
selection component 1114 selects the carrier from among the
plurality of unlicensed carriers by determining channel
availability of channels associated with the plurality of
unlicensed carriers, where a channel is available when an energy of
the channel is lower than an energy threshold, and selecting the
carrier associated with the channel for transmission of the UL data
(e.g., at 1168 and 1170 via the data communication component 1110)
based on at least one of the channel availability or a carrier
priority.
[0122] The resource management component 1116 receives at 1172, via
the reception component 1104 at 1152, configuration information
from a serving base station (e.g., eNB 1150) adjusting a number of
resource blocks to monitor for receiving the UL grant (e.g., at
1174 via the grant management component 1108). The grant management
component 1108 monitors for the UL grant based on the received
configuration information adjusting the number of resource blocks
to monitor for receiving the UL grant via 1174.
[0123] The apparatus may include additional components that perform
each of the blocks of the algorithm in the aforementioned
flowcharts of FIGS. 8-10. As such, each block in the aforementioned
flowcharts of FIGS. 8-10 may be performed by a component and the
apparatus may include one or more of those components. The
components may be one or more hardware components specifically
configured to carry out the stated processes/algorithm, implemented
by a processor configured to perform the stated
processes/algorithm, stored within a computer-readable medium for
implementation by a processor, or some combination thereof.
[0124] FIG. 12 is a diagram 1200 illustrating an example of a
hardware implementation for an apparatus 1102' employing a
processing system 1214. The processing system 1214 may be
implemented with a bus architecture, represented generally by the
bus 1224. The bus 1224 may include any number of interconnecting
buses and bridges depending on the specific application of the
processing system 1214 and the overall design constraints. The bus
1224 links together various circuits including one or more
processors and/or hardware components, represented by the processor
1204, the components 1104, 1106, 1108, 1110, 1112, 1114, 1116, and
the computer-readable medium/memory 1206. The bus 1224 may also
link various other circuits such as timing sources, peripherals,
voltage regulators, and power management circuits, which are well
known in the art, and therefore, will not be described any
further.
[0125] The processing system 1214 may be coupled to a transceiver
1210. The transceiver 1210 is coupled to one or more antennas 1220.
The transceiver 1210 provides a means for communicating with
various other apparatus over a transmission medium. The transceiver
1210 receives a signal from the one or more antennas 1220, extracts
information from the received signal, and provides the extracted
information to the processing system 1214, specifically the
reception component 1104. In addition, the transceiver 1210
receives information from the processing system 1214, specifically
the transmission component 1106, and based on the received
information, generates a signal to be applied to the one or more
antennas 1220. The processing system 1214 includes a processor 1204
coupled to a computer-readable medium/memory 1206. The processor
1204 is responsible for general processing, including the execution
of software stored on the computer-readable medium/memory 1206. The
software, when executed by the processor 1204, causes the
processing system 1214 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 1206 may also be used for storing data that is
manipulated by the processor 1204 when executing software. The
processing system 1214 further includes at least one of the
components 1104, 1106, 1108, 1110, 1112, 1114, 1116. The components
may be software components running in the processor 1204,
resident/stored in the computer readable medium/memory 1206, one or
more hardware components coupled to the processor 1204, or some
combination thereof. The processing system 1214 may be a component
of the UE 350 and may include the memory 360 and/or at least one of
the TX processor 368, the RX processor 356, and the
controller/processor 359.
[0126] In one configuration, the apparatus 1102/1102' for wireless
communication includes means for receiving a DL grant for a
secondary carrier and a UL grant for the secondary carrier, where
the DL grant is received on the secondary carrier and the UL grant
is received on a primary carrier, means for receiving DL data on
the secondary carrier after receiving the DL grant on the secondary
carrier, and means for transmitting UL data on the secondary
carrier after receiving the UL grant on the primary carrier. The
apparatus 1102/1102' further includes means for receiving
information about at least one of a set of DCI formats or DCI
format sizes of respective DCI messages to monitor on each subframe
on each carrier, and means for monitoring for at least one of the
UL grant or the DL grant based on the information. The apparatus
1102/1102' further includes means for receiving information on a
number of blind decodes to perform per subframe, and means for
blind decoding based on the number of blind decodes to detect at
least one of the DL grant or the UL grant. The apparatus 1102/1102'
further includes means for receiving, on the primary carrier, a DL
grant indicator, where the DL grant indicator indicates whether the
UE should monitor at least one of the primary carrier or the
secondary carrier for the DL grant. The apparatus 1102/1102'
further includes means for selecting a carrier from among the
plurality of unlicensed carriers as the secondary carrier to
transmit the UL data, where the UL grant received on the primary
carrier corresponds to a plurality of unlicensed carriers. The
apparatus 1102/1102' further includes means for receiving
configuration information from a serving base station adjusting a
number of resource blocks to monitor for receiving the UL grant,
and means for monitoring for the UL grant based on the received
configuration information adjusting the number of resource blocks
to monitor for receiving the UL grant.
[0127] The aforementioned means may be one or more of the
aforementioned components of the apparatus 1102 and/or the
processing system 1214 of the apparatus 1102' configured to perform
the functions recited by the aforementioned means. As described
supra, the processing system 1214 may include the TX Processor 368,
the RX Processor 356, and the controller/processor 359. As such, in
one configuration, the aforementioned means may be the TX Processor
368, the RX Processor 356, and the controller/processor 359
configured to perform the functions recited by the aforementioned
means.
[0128] FIG. 13 is a flow chart 1300 of a method of wireless
communication. The method may be performed by a base station (e.g.,
the base station 102, the eNB 754 104, the apparatus 1602/1602').
At block 1301, one or more additional methods discussed infra may
be performed. Blocks with dotted lines may include optional
features or steps.
[0129] In one aspect, at block 1302, the eNB may send, on the
primary carrier, a DL grant indicator, where the DL grant indicator
indicates whether the UE should monitor at least one of the primary
carrier or the secondary carrier for the DL grant. In an aspect,
the DL grant indicator is sent in a DCI message on the primary
carrier in a common search space and is protected with an RNTI that
is known to a group of user equipments. In an aspect, the DL grant
indicator is received on the primary carrier in a search space that
is specific to a user equipment.
[0130] For example, as discussed supra, in self-scheduling for DL
communication, the eNB may send a cross-carrier indicator to the UE
on the PCC to indicate that a DL grant will be sent on the SCC. For
example, as discussed supra, because presence or absence of a DL
grant on the SCC is indicated in the cross-carrier indicator
received on the PCC, the UE may monitor for the DL grant on the SCC
based on the cross-carrier indicator. For example, as discussed
supra, the eNB may include the cross-carrier indicator in a new DCI
message with a new format and transmit the new DCI message with the
new format on the PCC in the common search space, and the
cross-carrier indicator may be protected with a new RNTI that is
known to a group of UEs. For example, as discussed supra, the eNB
may provide separate indication to UE by sending a DCI message
including a cross-carrier indicator in a UE-specific search space,
instead of sending the DCI message in the common search space.
[0131] At block 1304, the eNB sends a DL grant for a secondary
carrier and a UL grant for the secondary carrier, where the DL
grant is transmitted on the secondary carrier and the UL grant is
transmitted on a primary carrier. For example, as discussed supra,
the eNB may transmit, on a secondary carrier, a DL grant for the
secondary carrier, and transmit, on a primary carrier, a UL grant
for the secondary carrier. For example, referring back to FIG. 7,
the eNB 754 may send, at 762, a UL grant to the UE 752 in the
control region 712 of the PCC, where the UL grant is for UL
communication on the SCC, and may send, at 772, a DL grant to the
UE 752 in the control region 722 of the SCC, where the DL grant is
for DL communication on the SCC.
[0132] At block 1306, the eNB sends DL data on the secondary
carrier after sending the DL grant on the secondary carrier. For
example, as discussed supra, the eNB may send DL data on the
secondary carrier based on the DL grant, according to the
self-scheduling mode. For example, referring back to FIG. 7, after
sending the DL grant on the SCC, the eNB 754 may send, at 774, DL
data in the data region 724 of the SCC based on the DL grant, as
indicated by the arrow 728.
[0133] At block 1308, the eNB receives UL data on the secondary
carrier after sending the UL grant on the primary carrier. For
example, as discussed supra, according to the cross-carrier
scheduling mode, the eNB may send, on a primary carrier, a UL grant
for the secondary carrier and send UL data on the secondary carrier
based on the UL grant. For example, referring back to FIG. 7, after
sending the UL grant on the PCC, the eNB 754 may receive, at 764,
based on the UL grant, UL data in the data region 724 of the SCC,
as indicated by the arrow 726.
[0134] In an aspect, the primary carrier is a licensed carrier, and
the secondary carrier is an unlicensed carrier. In an aspect, the
DL grant and the UL grant are transmitted from the eNB using a
configuration where DL grants are communicated on the secondary
carrier and UL grants are communicated on the primary carrier. In
an aspect, the DL grant and the UL grant are transmitted from the
eNB using a configuration where DL grants are scheduled by
self-scheduling on the secondary carrier and UL grants are
scheduled by cross-carrier scheduling on the primary carrier. For
example, as discussed supra, the primary carrier may be a licensed
carrier (e.g., a PCC) and the secondary carrier may be an
unlicensed carrier (e.g., an SCC).
[0135] In an aspect, the secondary carrier to receive the UL data
is a carrier selected among a plurality of unlicensed carriers, and
the UL grant sent on the primary carrier is specified for the
plurality of unlicensed carriers. In such an aspect, the eNB is
configured to blindly detect the selected carrier. For example, as
discussed supra, when the UE receives a UL grant, the UE may be
configured to determine whether the UL grant is mapped to a group
of unlicensed carriers. For example, as discussed supra, the eNB
may blind detect the unlicensed carrier that the UE uses to
transmit the UL data.
[0136] FIG. 14A is a flow chart 1400 of a method of wireless
communication expanding from the flow chart 1300 of FIG. 13,
according to an aspect of the disclosure. The method may be
performed by a base station (e.g., the base station 102, the eNB
754, the apparatus 1602/1602'). The flow chart 1400 expands from
block 1301 of FIG. 13. For example, the method in the flow chart
1400 may be performed to provide information used to monitor for a
DL grant and/or a UL grant, such that the UE may receive the DL
grant and the UL grant when the DL grant and the UL grant is sent
at block 1304 of FIG. 13. In an aspect, the base station may
continue at block 1302 or block 1304 of FIG. 13 after performing
the features of the flow chart 1400.
[0137] At block 1402, the eNB sends information about a set of DCI
formats or DCI format sizes to monitor on each subframe on each
carrier. In an aspect, each of the DCI format sizes is specific to
a transmission mode. For example, as discussed supra, if a DL grant
is communicated on a first carrier and a UL grant is communicated
on a second carrier different from the first carrier, the UE may
search for a format size of a DCI message for the DL grant on the
first carrier and additionally search for a format size of a DCI
message for the UL grant on the second carrier. For example, in one
aspect, the UE may receive the information about the at least one
of a set of DCI formats or DCI format sizes of respective DCI
messages by analyzing on the DCI messages received by the UE. For
example, as discussed supra, the UE may be configured to search on
the SCC for a DCI format size that is specific to a TM, in order to
monitor for the UL grant and/or the DL grant, without searching for
a fallback mode format size of a DCI message.
[0138] FIG. 14B is a flow chart 1450 of a method of wireless
communication expanding from the flow chart 1300 of FIG. 13,
according to an aspect of the disclosure. The method may be
performed by a base station (e.g., the base station 102, the eNB
754, the apparatus 1602/1602'). The flow chart 1450 expands from
block 1301 of FIG. 13. For example, the method in the flow chart
1450 may be performed to provide configuration for the UE to
perform blind decodes to detect a DL grant and/or a UL grant, such
that the UE may receive the DL grant and the UL grant when the DL
grant and the UL grant is sent at block 1304 of FIG. 13. In an
aspect, the base station may continue at block 1302 or block 1304
of FIG. 13 after performing the features of the flow chart
1450.
[0139] At block 1452, the eNB sends configuration information,
indicating a maximum number of blind decodes to be performed at the
UE per subframe to detect at least one of the DL grant or the UL
grant. For example, as discussed supra, the eNB may provide the UE
with blind decode information on a number of blind decodes (e.g., a
maximum number of blind decodes) to perform per subframe, to detect
a UL grant and/or a DL grant. For example, as discussed supra,
according to the blind decode information, the UE may decode all
candidates in some subframes, and may decode a subset of
candidates, based on the number of blind decodes specified in the
blind decode information.
[0140] FIG. 15A is a flow chart 1500 of a method of wireless
communication expanding from the flow chart 1300 of FIG. 13,
according to an aspect of the disclosure. The method may be
performed by a base station (e.g., the base station 102, the eNB
754, the apparatus 1602/1602'). The flow chart 1500 expands from
block 1301 of FIG. 13. For example, the method in the flow chart
1500 may be performed to configure transmission of a UL grant and a
DL grant at block 1304 of FIG. 13. In an aspect, the base station
may continue at block 1302 or block 1304 of FIG. 13 after
performing the features of the flow chart 1500.
[0141] At block 1504, the eNB selects an UL/DL grant configuration
based on a TDD subframe configuration. In such an aspect, the UL/DL
grant configuration includes sending DL grants on the secondary
carrier and UL grants on the primary carrier when the TDD subframe
configuration includes more UL subframes than DL subframes, and the
UL/DL grant configuration includes sending DL grants on the
secondary carrier and UL grants on the secondary carrier when the
TDD subframe configuration includes more UL subframes than DL
subframes. In an aspect, a scheduling mode is configured
independently for each of available carriers including the primary
carrier and the secondary carrier. In an aspect, the scheduling
mode is configured based on at least one of interference or channel
availability in each of the available carriers. In an aspect, a
scheduling mode is configured independently for each of available
carriers including the primary carrier and the secondary carrier,
and independently for the UL grant and the DL grant.
[0142] For example, as discussed supra, the eNB may configure the
scheduling mode as a function of TDD subframe configuration. For
example, as discussed supra, if the SCell uses a DL heavy
configuration (E.g., a configuration with more DL subframes than
other types of subframes), the SCell may schedule UL data
communication on an unlicensed carrier using a UL grant on the
unlicensed carrier. For example, as discussed supra, if the SCell
uses a UL heavy TDD configuration (E.g., a configuration with more
UL subframes than other types of subframes), the PCell may utilize
cross-carrier scheduling for UL communication. For example, as
discussed supra, the eNB may configure the scheduling mode
independently for each of carriers, where the carriers may include
a licensed carrier (e.g., the PCC) and one or more unlicensed
carriers (e.g., the SCC). For example, as discussed supra, the eNB
may configure the scheduling mode independently for each of
carriers based on signal interference and channel occupancy
observed in each carrier.
[0143] FIG. 15B is a flow chart 1550 of a method of wireless
communication expanding from the flow chart 1300 of FIG. 13,
according to an aspect of the disclosure. The method may be
performed by a base station (e.g., the base station 102, the eNB
754, the apparatus 1602/1602'). The flow chart 1550 expands from
block 1301 of FIG. 13. For example, the method in the flow chart
1550 may be performed to provide the UE with information used to
monitor for a UL grant, such that the UE may receive the UL grant
when the UL grant is sent at block 1304 of FIG. 13. In an aspect,
the base station may continue at block 1302 or block 1304 of FIG.
13 after performing the features of the flow chart 1550.
[0144] At block 1552, the eNB sends configuration information
adjusting a number of resources the UE is to monitor for the UL
grant. For example, as discussed supra, a scalable EPDCCH design
may be used such that an eNB may adjust the number of
RBs/candidates to be monitored by the UE for a defined set of
subframes which carry UL grants. For example, as discussed supra,
when the UE receives the EPDCCH from the eNB, the UE determines,
based on the EPDCCH, a certain set of RBs to monitor for subframes
that may carry UL grants.
[0145] At block 1554, the eNB configures a number of candidates or
aggregation levels to monitor in a PDCCH. For example, as discussed
supra, the eNB may configure a number of candidates or aggregation
levels to monitor in a PDCCH. Based on the number of candidates or
the aggregation levels, the UE may monitor for the UL grant.
[0146] At block 1556, the eNB configures at least one of a number
of sets of EPDCCHs, a number of RBs for each set of EPDCCHs, a type
of EPDCCH, or a number of candidates or aggregation levels for
EPDCCH monitoring. In an aspect, the number of resources to monitor
depends on at least one of a TDD subframe configuration or a number
of active unlicensed carriers. For example, as discussed supra, the
eNB may configure at least one of a number of sets of EPDCCHs, a
number of RBs for each set of EPDCCHs, a type of EPDCCH, or a
number of candidates or aggregation levels for EPDCCH
monitoring.
[0147] FIG. 16 is a conceptual data flow diagram 1600 illustrating
the data flow between different means/components in an exemplary
apparatus 1602. The apparatus may be an eNB. The apparatus includes
a reception component 1604, a transmission component 1606, a grant
management component 1608, a data communication component 1610, a
grant indicator component 1612, a grant configuration component
1614, and a resource management component 1616.
[0148] The grant management component 1608 sends to the UE 1650 at
1652 and 1654, via the transmission component 1606, a DL grant for
a secondary carrier and a UL grant for the secondary carrier, where
the DL grant is transmitted on the secondary carrier and the UL
grant is transmitted on a primary carrier. The data communication
component 1610 sends to the UE 1650 at 1656 and 1654, via the
transmission component 1606, DL data on the secondary carrier after
sending the DL grant on the secondary carrier. In an aspect, the
data communication component 1610 may communicate with the grant
management component 1608, at 1674, to schedule transmission of DL
data. The data communication component 1610 receives from the UE
1650 1658 and 1660, via the reception component 1604, UL data on
the secondary carrier after sending the UL grant on the primary
carrier. In an aspect, the primary carrier is a licensed carrier,
and the secondary carrier is an unlicensed carrier. In an aspect,
the DL grant and the UL grant are transmitted from the eNB using a
configuration where DL grants are communicated on the secondary
carrier and UL grants are communicated on the primary carrier. In
an aspect, the DL grant and the UL grant are transmitted from the
eNB using a configuration where DL grants are scheduled by
self-scheduling on the secondary carrier and UL grants are
scheduled by cross-carrier scheduling on the primary carrier.
[0149] In an aspect, the secondary carrier to receive the UL data
is a carrier selected among a plurality of unlicensed carriers, and
the UL grant sent on the primary carrier is specified for the
plurality of unlicensed carriers. In such an aspect, the grant
management component 1608 is configured to blindly detect the
selected carrier.
[0150] The grant management component 1608 sends via the
transmission component 1606 at 1652 and 1954 information about a
set of DCI formats or DCI format sizes to monitor on each subframe
on each carrier. In an aspect, each of the DCI format sizes is
specific to a transmission mode. The grant management component
1608 sends configuration via the transmission component 1606 at
1652 and 1654, indicating a maximum number of blind decodes to be
performed at the UE per subframe to detect at least one of the DL
grant or the UL grant.
[0151] The grant indicator component 1612 may send via the grant
management component 1608 and the transmission component 1606 at
1662, 1652, and 1654, on the primary carrier, a DL grant indicator,
where the DL grant indicator indicates whether the UE should
monitor at least one of the primary carrier or the secondary
carrier for the DL grant. In an aspect, the DL grant indicator is
sent in a DCI message on the primary carrier in a common search
space and is protected with an RNTI that is known to a group of
user equipments. In an aspect, the DL grant indicator is received
on the primary carrier in a search space that is specific to a user
equipment.
[0152] The grant configuration component 1614 selects an UL/DL
grant configuration based on a TDD subframe configuration via 1664
and 1668. In such an aspect, the UL/DL grant configuration includes
sending DL grants on the secondary carrier and UL grants on the
primary carrier when the TDD subframe configuration includes more
UL subframes than DL subframes, and the UL/DL grant configuration
includes sending DL grants on the secondary carrier and UL grants
on the secondary carrier when the TDD subframe configuration
includes more UL subframes than DL subframes. In an aspect, a
scheduling mode is configured independently for each of available
carriers including the primary carrier and the secondary carrier.
In an aspect, the scheduling mode is configured based on at least
one of interference or channel availability in each of the
available carriers. In an aspect, a scheduling mode is configured
independently for each of available carriers including the primary
carrier and the secondary carrier, and independently for the UL
grant and the DL grant.
[0153] The resource management component 1616 sends at 1670 and
1654 via the transmission component 1606 configuration information
adjusting a number of resources the UE is to monitor for the UL
grant. The resource management component 1616 configures (e.g., via
1672) a number of candidates or aggregation levels to monitor in a
PDCCH. The resource management component 1616 configures (e.g., via
1672) at least one of a number of sets of EPDCCHs, a number of RBs
for each set of EPDCCHs, a type of EPDCCH, or a number of
candidates or aggregation levels for EPDCCH monitoring. In an
aspect, the number of resources to monitor depends on at least one
of a TDD subframe configuration or a number of active unlicensed
carriers.
[0154] The apparatus may include additional components that perform
each of the blocks of the algorithm in the aforementioned
flowcharts of FIGS. 13-15. As such, each block in the
aforementioned flowcharts of FIGS. 13-15 may be performed by a
component and the apparatus may include one or more of those
components. The components may be one or more hardware components
specifically configured to carry out the stated
processes/algorithm, implemented by a processor configured to
perform the stated processes/algorithm, stored within a
computer-readable medium for implementation by a processor, or some
combination thereof.
[0155] FIG. 17 is a diagram 1700 illustrating an example of a
hardware implementation for an apparatus 1602' employing a
processing system 1714. The processing system 1714 may be
implemented with a bus architecture, represented generally by the
bus 1724. The bus 1724 may include any number of interconnecting
buses and bridges depending on the specific application of the
processing system 1714 and the overall design constraints. The bus
1724 links together various circuits including one or more
processors and/or hardware components, represented by the processor
1704, the components 1604, 1606, 1608, 1610, 1612, 1614, 1616, and
the computer-readable medium/memory 1706. The bus 1724 may also
link various other circuits such as timing sources, peripherals,
voltage regulators, and power management circuits, which are well
known in the art, and therefore, will not be described any
further.
[0156] The processing system 1714 may be coupled to a transceiver
1710. The transceiver 1710 is coupled to one or more antennas 1720.
The transceiver 1710 provides a means for communicating with
various other apparatus over a transmission medium. The transceiver
1710 receives a signal from the one or more antennas 1720, extracts
information from the received signal, and provides the extracted
information to the processing system 1714, specifically the
reception component 1604. In addition, the transceiver 1710
receives information from the processing system 1714, specifically
the transmission component 1606, and based on the received
information, generates a signal to be applied to the one or more
antennas 1720. The processing system 1714 includes a processor 1704
coupled to a computer-readable medium/memory 1706. The processor
1704 is responsible for general processing, including the execution
of software stored on the computer-readable medium/memory 1706. The
software, when executed by the processor 1704, causes the
processing system 1714 to perform the various functions described
supra for any particular apparatus. The computer-readable
medium/memory 1706 may also be used for storing data that is
manipulated by the processor 1704 when executing software. The
processing system 1714 further includes at least one of the
components 1604, 1606, 1608, 1610, 1612, 1614, 1616. The components
may be software components running in the processor 1704,
resident/stored in the computer readable medium/memory 1706, one or
more hardware components coupled to the processor 1704, or some
combination thereof. The processing system 1714 may be a component
of the eNB 310 and may include the memory 376 and/or at least one
of the TX processor 316, the RX processor 370, and the
controller/processor 375.
[0157] In one configuration, the apparatus 1602/1602' for wireless
communication includes means for sending a DL grant for a secondary
carrier and a UL grant for the secondary carrier, where the DL
grant is transmitted on the secondary carrier and the UL grant is
transmitted on a primary carrier, means for sending DL data on the
secondary carrier after sending the DL grant on the secondary
carrier, and means for receiving UL data on the secondary carrier
after sending the UL grant on the primary carrier. The apparatus
1602/1602' further includes means for sending information about a
set of DCI formats or DCI format sizes to monitor on each subframe
on each carrier. The apparatus 1602/1602' further includes means
for sending configuration information, indicating a maximum number
of blind decodes to be performed at the UE per subframe to detect
at least one of the DL grant or the UL grant. The apparatus
1602/1602' further includes means for sending, on the primary
carrier, a DL grant indicator, where the DL grant indicator
indicates whether the UE should monitor at least one of the primary
carrier or the secondary carrier for the DL grant. The apparatus
1602/1602' further includes means for selecting an UL/DL grant
configuration based on a TDD subframe configuration. The apparatus
1602/1602' further includes means for sending configuration
information adjusting a number of resources the UE is to monitor
for the UL grant. The apparatus 1602/1602' further includes means
for configuring a number of candidates or aggregation levels to
monitor in a PDCCH, and means for configuring at least one of a
number of sets of EPDCCHs, a number of RBs for each set of EPDCCHs,
a type of EPDCCH, or a number of candidates or aggregation levels
for EPDCCH monitoring.
[0158] The aforementioned means may be one or more of the
aforementioned components of the apparatus 1602 and/or the
processing system 1714 of the apparatus 1602' configured to perform
the functions recited by the aforementioned means. As described
supra, the processing system 1714 may include the TX Processor 316,
the RX Processor 370, and the controller/processor 375. As such, in
one configuration, the aforementioned means may be the TX Processor
316, the RX Processor 370, and the controller/processor 375
configured to perform the functions recited by the aforementioned
means.
[0159] It is understood that the specific order or hierarchy of
blocks in the processes/flowcharts disclosed is an illustration of
exemplary approaches. Based upon design preferences, it is
understood that the specific order or hierarchy of blocks in the
processes/flowcharts may be rearranged. Further, some blocks may be
combined or omitted. The accompanying method claims present
elements of the various blocks in a sample order, and are not meant
to be limited to the specific order or hierarchy presented.
[0160] The previous description is provided to enable any person
skilled in the art to practice the various aspects described
herein. Various modifications to these aspects will be readily
apparent to those skilled in the art, and the generic principles
defined herein may be applied to other aspects. Thus, the claims
are not intended to be limited to the aspects shown herein, but is
to be accorded the full scope consistent with the language claims,
wherein reference to an element in the singular is not intended to
mean "one and only one" unless specifically so stated, but rather
"one or more." The word "exemplary" is used herein to mean "serving
as an example, instance, or illustration." Any aspect described
herein as "exemplary" is not necessarily to be construed as
preferred or advantageous over other aspects. Unless specifically
stated otherwise, the term "some" refers to one or more.
Combinations such as "at least one of A, B, or C," "one or more of
A, B, or C," "at least one of A, B, and C," "one or more of A, B,
and C," and "A, B, C, or any combination thereof" include any
combination of A, B, and/or C, and may include multiples of A,
multiples of B, or multiples of C. Specifically, combinations such
as "at least one of A, B, or C," "one or more of A, B, or C," "at
least one of A, B, and C," "one or more of A, B, and C," and "A, B,
C, or any combination thereof" may be A only, B only, C only, A and
B, A and C, B and C, or A and B and C, where any such combinations
may contain one or more member or members of A, B, or C. All
structural and functional equivalents to the elements of the
various aspects described throughout this disclosure that are known
or later come to be known to those of ordinary skill in the art are
expressly incorporated herein by reference and are intended to be
encompassed by the claims. Moreover, nothing disclosed herein is
intended to be dedicated to the public regardless of whether such
disclosure is explicitly recited in the claims. The words "module,"
"mechanism," "element," "device," and the like may not be a
substitute for the word "means." As such, no claim element is to be
construed as a means plus function unless the element is expressly
recited using the phrase "means for."
* * * * *